U.S. patent application number 17/467648 was filed with the patent office on 2021-12-23 for method and apparatus for plmn selection and cell (re)selection.
The applicant listed for this patent is FG Innovation Company Limited. Invention is credited to Hung-Chen CHEN, Mei-Ju SHIH, Yung-Lan TSENG.
Application Number | 20210400570 17/467648 |
Document ID | / |
Family ID | 1000005826211 |
Filed Date | 2021-12-23 |
United States Patent
Application |
20210400570 |
Kind Code |
A1 |
SHIH; Mei-Ju ; et
al. |
December 23, 2021 |
METHOD AND APPARATUS FOR PLMN SELECTION AND CELL (RE)SELECTION
Abstract
A method and an apparatus for wireless communications are
provided. The method is performed by a UE and includes: reading
system information of a plurality of cells on a first carrier
frequency to obtain identification information of a plurality of
PLMNs; reporting, by an AS entity of the UE, the identification
information of the plurality of PLMNs to a NAS entity of the UE;
selecting, by the NAS of the UE, one of the plurality of PLMNs as a
selected PLMN; searching for the plurality of cells on the first
carrier frequency during a cell selection procedure; and selecting
a suitable cell belonging to the selected PLMN from the plurality
of cells on the first carrier frequency based on the cell selection
procedure.
Inventors: |
SHIH; Mei-Ju; (Taipei,
TW) ; TSENG; Yung-Lan; (Taipei, TW) ; CHEN;
Hung-Chen; (Taipei, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
FG Innovation Company Limited |
Tuen Mun |
|
HK |
|
|
Family ID: |
1000005826211 |
Appl. No.: |
17/467648 |
Filed: |
September 7, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16728961 |
Dec 27, 2019 |
11166227 |
|
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17467648 |
|
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62788223 |
Jan 4, 2019 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H04W 84/042 20130101;
H04W 72/0453 20130101; H04W 48/02 20130101; H04W 48/16 20130101;
H04W 76/25 20180201; H04W 76/27 20180201; H04W 76/11 20180201; H04W
16/14 20130101 |
International
Class: |
H04W 48/16 20060101
H04W048/16; H04W 76/11 20060101 H04W076/11; H04W 72/04 20060101
H04W072/04; H04W 76/25 20060101 H04W076/25; H04W 48/02 20060101
H04W048/02; H04W 76/27 20060101 H04W076/27; H04W 16/14 20060101
H04W016/14 |
Claims
1. A User Equipment (UE) for wireless communications, the UE
comprising: one or more non-transitory computer-readable media
having computer-executable instructions embodied thereon; and at
least one processor coupled to the one or more non-transitory
computer-readable media, and configured to execute the
computer-executable instructions to: read system information of a
plurality of cells on a first carrier frequency to obtain
identification information of a plurality of Public Land Mobile
Networks (PLMNs); report, by an Access Stratum (AS) entity of the
UE, the identification information of the plurality of PLMNs to a
Non-Access Stratum (NAS) entity of the UE; select, by the NAS of
the UE, one of the plurality of PLMNs as a selected PLMN; search
for the plurality of cells on the first carrier frequency during a
cell selection procedure; and select a suitable cell belonging to
the selected PLMN from the plurality of cells on the first carrier
frequency based on the cell selection procedure.
2. The UE of claim 1, wherein the at least one processor is further
configured to execute the computer-executable instructions to:
perform a cell reselection procedure to select a new suitable cell,
wherein the new suitable cell is a non-highest-ranked cell among
all cells on the first carrier frequency and belongs to one of the
selected PLMN and an equivalent PLMN that is indicated as being
equivalent to a registered PLMN of the UE.
3. The UE of claim 2, wherein the non-highest-ranked cell and a
highest-ranked cell on the first carrier frequency belong to two
PLMNs of the plurality of PLMNs.
4. The UE of claim 1, wherein the at least one processor is further
configured to execute the computer-executable instructions to:
perform a cell reselection procedure to select a new suitable cell,
the cell reselection procedure comprising: determining whether the
new suitable cell is on a second carrier frequency after
determining that a total number of non-suitable cells on the first
carrier frequency reaches a specific number.
5. The UE of claim 4, wherein the cell reselection procedure
further comprises: selecting, from one or more cells on the second
carrier frequency, a highest-ranked cell as the new suitable cell
when the highest-ranked cell belongs to one of the selected PLMN
and an equivalent PLMN that is indicated as being equivalent to a
registered PLMN of the UE; determining that the highest-ranked cell
is a non-suitable cell when the highest-ranked cell does not belong
to one of the selected PLMN and the equivalent PLMN; and
prohibiting the non-suitable cell from being selected as the new
suitable cell for a period of time.
6. The UE of claim 5, wherein the cell reselection procedure
further comprises: determining the highest-ranked cell by ranking
the one or more cells on the second carrier frequency based on a
received radio signal quality.
7. The UE of claim 4, wherein the at least one processor is further
configured to execute the computer-executable instructions to:
deprioritize the first carrier frequency for cell reselection for a
period of time after determining that the total number of
non-suitable cells on the first carrier frequency reaches the
specific number.
8. The UE of claim 1, wherein the system information includes
PLMN-type information indicating at least one PLMN type associated
with the plurality of cells.
9. The UE of claim 1, wherein the at least one processor is further
configured to execute the computer-executable instructions to:
provide a message by the NAS entity of the UE to the AS entity of
the UE, the message indicating which of one or more PLMN types are
supported by the UE, wherein the one or more PLMN types include a
public PLMN type, a private PLMN type, and a public and private
PLMN type.
10. The UE of claim 1, wherein the first carrier frequency is an
unlicensed carrier frequency.
11. A method performed by a User Equipment (UE) for wireless
communications, the method comprising: reading system information
of a plurality of cells on a first carrier frequency to obtain
identification information of a plurality of Public Land Mobile
Networks (PLMNs); reporting, by an Access Stratum (AS) entity of
the UE, the identification information of the plurality of PLMNs to
a Non-Access Stratum (NAS) entity of the UE; selecting, by the NAS
of the UE, one of the plurality of PLMNs as a selected PLMN;
searching for the plurality of cells on the first carrier frequency
during a cell selection procedure; and selecting a suitable cell
belonging to the selected PLMN from the plurality of cells on the
first carrier frequency based on the cell selection procedure.
12. The method of claim 11, further comprising: performing a cell
reselection procedure to select a new suitable cell, wherein the
new suitable cell is a non-highest-ranked cell among all cells on
the first carrier frequency and belongs to one of the selected PLMN
and an equivalent PLMN that is indicated as being equivalent to a
registered PLMN of the UE.
13. The method of claim 12, wherein the non-highest-ranked cell and
a highest-ranked cell on the first carrier frequency belong to two
PLMNs of the plurality of PLMNs.
14. The method of claim 11, further comprising: performing a cell
reselection procedure to select a new suitable cell, the cell
reselection procedure comprising: determining whether the new
suitable cell is on a second carrier frequency after determining
that a total number of non-suitable cells on the first carrier
frequency reaches a specific number.
15. The method of claim 14, wherein the cell reselection procedure
further comprises: selecting, from one or more cells on the second
carrier frequency, a highest-ranked cell as the new suitable cell
when the highest-ranked cell belongs to one of the selected PLMN
and an equivalent PLMN that is indicated as being equivalent to a
registered PLMN of the UE; determining that the highest-ranked cell
is a non-suitable cell when the highest-ranked cell does not belong
to one of the selected PLMN and the equivalent PLMN; and
prohibiting the non-suitable cell from being selected as the new
suitable cell for a period of time.
16. The method of claim 15, wherein the cell reselection procedure
further comprises: determining the highest-ranked cell by ranking
the one or more cells on the second carrier frequency based on a
received radio signal quality.
17. The method of claim 14, further comprising: deprioritizing the
first carrier frequency for cell reselection for a period of time
after determining that the total number of non-suitable cells on
the first carrier frequency reaches the specific number.
18. The method of claim 11, wherein the system information includes
PLMN-type information indicating at least one PLMN type associated
with the plurality of cells.
19. The method of claim 11, further comprising: providing a message
by the NAS entity of the UE to the AS entity of the UE, the message
indicating which of one or more PLMN types are supported by the UE,
wherein the one or more PLMN types include a public PLMN type, a
private PLMN type, and a public and private PLMN type.
20. The method of claim 11, wherein the first carrier frequency is
an unlicensed carrier frequency.
Description
CROSS-REFERENCE TO RELATED APPLICATION(S)
[0001] This application is a continuation application of U.S.
patent application Ser. No. 16/728,961 filed on Dec. 27, 2019,
which claims the benefit of and priority to a provisional U.S.
Patent Application Ser. No. 62/788,223, filed on Jan. 4, 2019, the
contents of all which are hereby fully incorporated herein by
reference for all purposes.
FIELD
[0002] The present disclosure generally relates to wireless
communications, and more particularly, to methods and apparatuses
for Public Land Mobile Network (PLMN) selection and cell
(re)selection.
BACKGROUND
[0003] Various efforts have been made to improve different aspects
of wireless communications (e.g., data rate, latency, reliability,
and mobility) for the next-generation (e.g., fifth generation (5G)
New Radio (NR)) wireless communication systems. For example, to
achieve higher capacity and promote higher spectrum utilization,
the next-generation wireless communication systems may be enabled
to operate on unlicensed spectrums. However, the current Radio
Resource Control (RRC)_IDLE or RRC_INACTIVE state to RRC_CONNECTED
state transition procedures, such as PLMN selection and cell
(re)selection procedures, may not be adequate for UEs attempting to
utilize the unlicensed spectrums to access the network in the
next-generation wireless communication systems.
[0004] Therefore, there is a need in the art for providing methods
and apparatuses for performing PLMN selection and cell
(re)selection on the unlicensed spectrum(s).
SUMMARY
[0005] The present disclosure is directed to methods and
apparatuses for PLMN selection and cell (re)selection.
[0006] According to an aspect of the present disclosure, a User
Equipment (UE) for wireless communications is provided. The UE
includes one or more non-transitory computer-readable media having
computer-executable instructions embodied thereon and at least one
processor coupled to the one or more non-transitory
computer-readable media. The at least one processor is configured
to execute the computer-executable instructions to read system
information of a plurality of cells on a first carrier frequency to
obtain identification information of a plurality of Public Land
Mobile Networks (PLMNs); report, by an Access Stratum (AS) entity
of the UE, the identification information of the plurality of PLMNs
to a Non-Access Stratum (NAS) entity of the UE; select, by the NAS
of the UE, one of the plurality of PLMNs as a selected PLMN; search
for the plurality of cells on the first carrier frequency during a
cell selection procedure; and select a suitable cell belonging to
the selected PLMN from the plurality of cells on the first carrier
frequency based on the cell selection procedure.
[0007] According to another aspect of the present disclosure, a
method performed by a UE for wireless communications is provided.
The method includes reading system information of a plurality of
cells on a first carrier frequency to obtain identification
information of a plurality of PLMNs; reporting, by an AS entity of
the UE, the identification information of the plurality of PLMNs to
a NAS entity of the UE; selecting, by the NAS of the UE, one of the
plurality of PLMNs as a selected PLMN; searching for the plurality
of cells on the first carrier frequency during a cell selection
procedure; and selecting a suitable cell belonging to the selected
PLMN from the plurality of cells on the first carrier frequency
based on the cell selection procedure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] Aspects of the present disclosure are best understood from
the following detailed description when read with the accompanying
figures. Various features are not drawn to scale. Dimensions of
various features may be arbitrarily increased or reduced for
clarity of discussion.
[0009] FIG. 1 illustrates a flowchart for a method of performing
PLMN selection and cell (re)selection procedures on an unlicensed
spectrum, in accordance with an example implementation of the
present disclosure.
[0010] FIG. 2A is a schematic diagram illustrating a PLMN selection
procedure, in accordance with an example implementation of the
present disclosure.
[0011] FIG. 2B is a schematic diagram illustrating a cell selection
procedure, in accordance with an example implementation of the
present disclosure.
[0012] FIG. 3 illustrates a flowchart for a method of performing
PLMN selection and cell (re)selection procedures on an unlicensed
spectrum, in accordance with an example implementation of the
present disclosure.
[0013] FIG. 4A illustrates a flowchart for a cell reselection
procedure, in accordance with an example implementation of the
present disclosure.
[0014] FIG. 4B illustrates a flowchart for a cell reselection
procedure, in accordance with an example implementation of the
present disclosure.
[0015] FIG. 5 illustrates a flowchart for a cell reselection
procedure performed when a UE cannot find a new suitable cell on a
carrier frequency, in accordance with an example implementation of
the present disclosure.
[0016] FIG. 6 is a schematic diagram illustrating a cell
reselection procedure, in accordance with an example implementation
of the present disclosure.
[0017] FIG. 7 is a schematic diagram illustrating a message flow
between the AS entity and the NAS entity of a UE, in accordance
with an example implementation of the present disclosure.
[0018] FIG. 8 is a block diagram illustrating a node for wireless
communication, in accordance with various aspects of the present
disclosure.
DETAILED DESCRIPTION
[0019] The following description contains specific information
pertaining to example implementations in the present disclosure.
The drawings in the present disclosure and their accompanying
detailed description are directed to merely example
implementations. However, the present disclosure is not limited to
merely these example implementations. Other variations and
implementations of the present disclosure will occur to those
skilled in the art. Unless noted otherwise, like or corresponding
elements among the figures may be indicated by like or
corresponding reference numerals. Moreover, the drawings and
illustrations in the present disclosure are generally not to scale
and are not intended to correspond to actual relative
dimensions.
[0020] For the purpose of consistency and ease of understanding,
like features may be identified (although, in some examples, not
shown) by the same numerals in the example figures. However, the
features in different implementations may be different in other
respects, and thus shall not be narrowly confined to what is shown
in the figures.
[0021] The description uses the phrases "in one implementation," or
"in some of the present implementations," which may each refer to
one or more of the same or different implementations. The term
"coupled" is defined as connected, whether directly or indirectly
through intervening components, and is not necessarily limited to
physical connections. The term "comprising," when utilized, means
"including, but not necessarily limited to"; it specifically
indicates open-ended inclusion or membership in the so-described
combination, group, series and the equivalent. The expression "at
least one of A, B and C" or "at least one of the following: A, B
and C" means "only A, or only B, or only C, or any combination of
A, B and C."
[0022] Additionally, for the purposes of explanation and
non-limitation, specific details, such as functional entities,
techniques, protocols, standard, and the like are set forth for
providing an understanding of the described technology. In other
examples, detailed description of well-known methods, technologies,
systems, architectures, and the like are omitted so as not to
obscure the description with unnecessary details.
[0023] Persons skilled in the art will immediately recognize that
any network function(s) or algorithm(s) described in the present
disclosure may be implemented by hardware, software or a
combination of software and hardware. Described functions may
correspond to modules which may be software, hardware, firmware, or
any combination thereof. The software implementation may comprise
computer-executable instructions stored on computer-readable medium
such as memory or other type of storage devices. For example, one
or more microprocessors or general-purpose computers with
communication processing capability may be programmed with
corresponding executable instructions and carry out the described
network function(s) or algorithm(s). The microprocessors or
general-purpose computers may be formed of Applications Specific
Integrated Circuitry (ASIC), programmable logic arrays, and/or
using one or more Digital Signal Processor (DSPs). Although some of
the example implementations described in this specification are
oriented to software installed and executing on computer hardware,
nevertheless, alternative example implementations implemented as
firmware or as hardware or combination of hardware and software are
well within the scope of the present disclosure.
[0024] The computer-readable medium includes but is not limited to
Random Access Memory (RAM), Read-Only Memory (ROM), Erasable
Programmable Read-Only Memory (EPROM), Electrically Erasable
Programmable Read-Only Memory (EEPROM), flash memory, Compact Disc
Read-Only Memory (CD-ROM), magnetic cassettes, magnetic tape,
magnetic disk storage, or any other equivalent medium capable of
storing computer-readable instructions.
[0025] A radio communication network architecture (e.g., a Long
Term Evolution (LTE) system, an LTE-Advanced (LTE-A) system, an
LTE-Advanced Pro system, or a 5G NR Radio Access Network (RAN))
typically includes at least one Base Station (BS), at least one UE,
and one or more optional network elements that provide connection
towards a network. The UE communicates with the network (e.g., a
Core Network (CN), an Evolved Packet Core (EPC) network, an Evolved
Universal Terrestrial Radio Access Network (E-UTRAN), a 5G Core
(5GC), or an internet), through a RAN established by one or more
BSs.
[0026] It should be noted that, in the present application, a UE
may include, but is not limited to, a mobile station, a mobile
terminal or device, or a user communication radio terminal. For
example, a UE may be a portable radio equipment, which includes,
but is not limited to, a mobile phone, a tablet, a wearable device,
a sensor, a vehicle, or a Personal Digital Assistant (PDA) with
wireless communication capability. The UE is configured to receive
and transmit signals over an air interface to one or more cells in
a radio access network.
[0027] A BS may be configured to provide communication services
according to at least one of the following Radio Access
Technologies (RATs): Worldwide Interoperability for Microwave
Access (WiMAX), Global System for Mobile communications (GSM, often
referred to as 2G), GSM Enhanced Data rates for GSM Evolution
(EDGE) Radio Access Network (GERAN), General Packet Radio Service
(GPRS), Universal Mobile Telecommunication System (UMTS, often
referred to as 3G) based on basic Wideband-Code Division Multiple
Access (W-CDMA), High-Speed Packet Access (HSPA), LTE, LTE-A, eLTE
(evolved LTE, e.g., LTE connected to 5GC), NR (often referred to as
5G), and/or LTE-A Pro. However, the scope of the present
application should not be limited to the above-mentioned
protocols.
[0028] A BS may include, but is not limited to, a node B (NB) as in
the UMTS, an evolved Node B (eNB) as in the LTE or LTE-A, a Radio
Network Controller (RNC) as in the UMTS, a Base Station Controller
(BSC) as in the GSM/GERAN, a ng-eNB as in an Evolved Universal
Terrestrial Radio Access (E-UTRA) BS in connection with the 5GC, a
next generation Node B (gNB) as in the 5G-RAN, and any other
apparatus capable of controlling radio communication and managing
radio resources within a cell. The BS may serve one or more UEs
through a radio interface.
[0029] The BS is operable to provide radio coverage to a specific
geographical area using a plurality of cells forming the radio
access network. The BS supports the operations of the cells. Each
cell is operable to provide services to at least one UE within its
radio coverage. More specifically, each cell (often referred to as
a serving cell) provides services to serve one or more UEs within
its radio coverage (e.g., each cell schedules the downlink and
optionally uplink resources to at least one UE within its radio
coverage for downlink and optionally uplink packet transmissions).
The BS can communicate with one or more UEs in the radio
communication system through the plurality of cells. A cell may
allocate Sidelink (SL) resources for supporting Proximity Service
(ProSe) or Vehicle to Everything (V2X) service. Each cell may have
overlapped coverage areas with other cells.
[0030] As discussed above, the frame structure for NR is to support
flexible configurations for accommodating various next-generation
(e.g., 5G) communication requirements, such as Enhanced Mobile
Broadband (eMBB), Massive Machine Type Communication (mMTC),
Ultra-Reliable and Low-Latency Communication (URLLC), while
fulfilling high reliability, high data rate and low latency
requirements. The Orthogonal Frequency-Division Multiplexing (OFDM)
technology as agreed in the 3.sup.rd Generation Partnership Project
(3GPP) may serve as a baseline for NR waveform. The scalable OFDM
numerology, such as the adaptive sub-carrier spacing, the channel
bandwidth, and the Cyclic Prefix (CP) may also be used.
Additionally, two coding schemes are considered for NR: (1)
Low-Density Parity-Check (LDPC) code and (2) Polar Code. The coding
scheme adaption may be configured based on the channel conditions
and/or the service applications.
[0031] Moreover, it is also considered that in a transmission time
interval TX of a single NR frame, a Downlink (DL) transmission
data, a guard period, and an Uplink (UL) transmission data should
at least be included, where the respective portions of the DL
transmission data, the guard period, the UL transmission data
should also be configurable, for example, based on the network
dynamics of NR. In addition, SL resources may also be provided in
an NR frame to support ProSe services or V2X services.
[0032] In addition, the terms "system" and "network" herein may be
used interchangeably. The term "and/or" herein is only an
association relationship for describing associated objects, and
represents that three relationships may exist. For example, A
and/or B may indicate that: A exists alone, A and B exist at the
same time, or B exists alone. In addition, the character "/" herein
generally represents that the former and latter associated objects
are in an "or" relationship.
[0033] On a licensed spectrum, a UE may perform a PLMN selection
procedure based on the signal strength of cells (e.g., the measured
Reference Signal Received Power (RSRP) from cells). The cells on
the licensed spectrum may broadcast the identification information
(e.g., PLMN Identities (IDs)) of the PLMNs and the UE's
preconfigured PLMNs. On each licensed carrier frequency, the AS
entity of the UE may report the PLMN IDs broadcast by the cell with
the strongest signal strength, to the NAS entity of the UE.
Generally, cells operating on a common licensed carrier frequency
may belong to the same PLMN.
[0034] There may be multiple PLMNs operating on one carrier
frequency. For example, one or more unlicensed RAT technologies
(e.g., standalone New Radio-Unlicensed (NR-U)) may be introduced,
meaning that multiple PLMNs may operate their own cells on the same
unlicensed spectrum. Thus, the PLMN selection and cell
(re)selection procedures on the unlicensed spectrum need to be
provided, especially considering the uncertainty of channel load
and channel sharing among multiple PLMNs. In another example, one
or more PLMNs may operate on the same carrier frequency if RAN
sharing scenarios are considered. PLMN(s) may be public PLMN(s)
and/or private PLMN(s). Thus, the PLMN selection and cell
(re)selection procedures when multiple PLMNs are operating on one
carrier frequency need to be provided. In the RAN sharing
scenarios, a RAN (or a cell) may be shared and operated by multiple
PLMNs.
[0035] In some of the implementations, the UE may camp on a
non-best cell on a carrier frequency (e.g., an unlicensed carrier
frequency) if the best cell does not belong to a selected PLMN or a
registered PLMN (or equivalent PLMN). The best cell may be the
highest-ranked cell among cells on the same carrier frequency. The
cells on the carrier frequency may be ranked by a received radio
signal quality and/or other measured metric value(s). For example,
the best cell (or highest-ranked cell) may be the cell having the
best received radio signal quality on the carrier frequency, while
the non-best cell (or the non-highest-ranked cell or lower-ranked
cell) may be the cell other than the best cell on the carrier
frequency.
[0036] It should be noted that the terms such as "best cell,"
"strongest cell," and "highest-ranked cell" may be interchangeable
in some of the present implementations. Similarly, the terms such
as "non-best cell," "non-strongest cell," "lower-ranked cell" and
"non-highest-ranked cell" may be interchangeable in some of the
present implementations.
[0037] In some of the implementations, all cells on a licensed
carrier frequency may belong to the same (equivalent) PLMN. Thus,
after the PLMN selection, the licensed carrier frequency may be
indirectly selected. The UE may then prioritize the cells, and camp
on the strongest cell on the licensed carrier frequency. Unlike the
licensed spectrum operations, one or more of the cells sharing the
same unlicensed carrier frequency may belong to different PLMNs. If
the UE prioritizes the cells and camps on the strongest cell on the
unlicensed carrier frequency after the PLMN selection, the UE may
waste time and consume extra power on searching for the suitable
cell, when the strongest cell does not belong to a
selected/registered/equivalent PLMN. In view of this, PLMN
selection and cell (re)selection methods for unlicensed spectrum
operations are provided in at least some of the present
implementations.
[0038] It should be noted that the PLMN selection and the cell
(re)selection methods described herein may be also applied to the
licensed spectrum operations.
[0039] FIG. 1 illustrates a flowchart for a method of performing
PLMN selection and cell (re)selection procedures on an unlicensed
spectrum, in accordance with an example implementation of the
present disclosure. As shown in FIG. 1, the method includes actions
102, 104, 106, 108 and 110, where actions 102, 104 and 106 may be
performed during a PLMN selection procedure, and actions 108 and
110 may be performed during a cell selection procedure.
[0040] In action 102, a UE may read system information of a
plurality of cells on a first carrier frequency to obtain
identification information of a plurality of PLMNs. In some of the
present implementations, the first carrier frequency may be an
unlicensed carrier frequency. The plurality of cells may include
the strongest cell and non-strongest cells. Each cell may broadcast
the identification information of a plurality of PLMNs in the
system information (e.g., System Information Block 1 (SIB1)).
[0041] In action 104, the AS entity of the UE may report the
identification information of the plurality of PLMNs to the NAS
entity of the UE. The PLMNs identified by the identification
information of the plurality of PLMNs reported by the AS entity of
the UE to the NAS entity of the UE may refer to the found PLMNs of
the UE. The NAS entity of the UE may be used to provide the upper
layer signaling (e.g., NAS signaling) between the UE and the core
network, and the AS entity of the UE may be used to provide the
lower layer signaling (e.g., RRC signaling) between the RAN and the
UE. For example, the AS entity may be used for transporting data
over the wireless connection and managing the radio resources. The
AS entity may include, for example, one or more layers of a
protocol stack including a physical (PHY) layer, a Medium Access
Control (MAC) layer, a Radio Link Control (RLC) layer, a Packet
Data Convergence Protocol (PDCP) layer, a Service Data Adaptation
Protocol (SDAP) layer and an RRC layer. Each of the AS entity and
the NAS entity of the UE may be implemented using electronic
hardware, computer software, or any combination thereof.
[0042] In action 106, the NAS entity of the UE may select one of
the plurality of PLMNs as a selected PLMN. For example, the NAS
entity of the UE may maintain or store a list of
registered/equivalent/subscribed PLMNs and select the PLMN which is
mapped to the list as the outcome (e.g., the selected PLMN) of the
PLMN selection procedure.
[0043] In action 108, the UE may search for the plurality of cells
on the first carrier frequency during a cell selection procedure.
The UE may not only search for the strongest cell but also search
for additional cells on the first carrier frequency during the cell
selection procedure. In some implementations, the additional cells
may or may not have a signal strength (e.g., RSRP, Reference Signal
Received Quality (RSRQ)) above a threshold (e.g., the additional
cells may fulfill the S criterion). The plurality of cells may be
searched based on certain (pre)configured or predefined rules. For
example, the plurality of cells may be the N-strongest (e.g., top
N) cells on the first carrier frequency, where N is a positive
integer. In some of the present implementations, the value of N may
be predefined (e.g., defined by 3GPP specifications), preconfigured
to the UE (e.g., stored in a Universal Subscriber Identity Module
(USIM) and/or stored in a Universal Integrated Circuit Card
(UICC)), configured by cell(s) (e.g., via system information and/or
via dedicated signaling), or determined based on UE
implementation.
[0044] In action 110, the UE may select a suitable cell belonging
to the selected PLMN from the plurality of cells on the first
carrier frequency as an outcome of the cell selection procedure.
The suitable cell may or may not be the strongest cell on the first
carrier frequency.
[0045] FIG. 2A is a schematic diagram illustrating a PLMN selection
procedure, in accordance with an example implementation of the
present disclosure. FIG. 2B is a schematic diagram illustrating a
cell selection procedure, in accordance with an example
implementation of the present disclosure.
[0046] In FIG. 2A, there are K cells C1, C2, C3, . . . , and CK on
carrier frequency f1. In the example implementation as illustrated
in FIGS. 2A and 2B, carrier frequency f1 may be an unlicensed
carrier frequency. However, this is only for illustrative purposes,
and not intended to limit the scope of the present disclosure. In
some other implementations, carrier frequency f1 may be a licensed
carrier frequency.
[0047] Each cell on carrier frequency f1 may broadcast the
identification information of its corresponding PLMN(s) in the
system information (e.g., SIB1). For example, cell C1 may broadcast
PLMN ID #1 of PLMN #1 to which cell C1 belongs; cell C2 may
broadcast PLMN ID #2 of PLMN #2 to which cell C2 belongs; cell C3
may broadcast PLMN ID #3 of PLMN #3 to which cell C3 belongs; and
cell CK may broadcast PLMN ID #2 of PLMN #2 to which cell CK
belongs. If a cell belongs to more than one PLMN, the cell may
broadcast the corresponding PLMN identification information in the
system information (e.g., SIB1).
[0048] In the example implementation, cells C1 through CK may be
ranked by a UE based on a received radio signal quality (e.g., RSRP
and/or RSRQ), for example, from the strongest to the weakest. The
UE may read the system information of the N1-strongest cells on
carrier frequency f1. The UE may obtain the identification
information of PLMNs from the system information broadcast by these
cells (e.g., N1-strongest cells). In some of the present
implementations, the value of N1 may be predefined (e.g., defined
by 3GPP specifications), preconfigured to the UE (e.g., stored in a
USIM and/or stored in a UICC), configured by cell(s) (e.g., via
system information and/or via dedicated signaling), or determined
based on UE implementation. For example, if N1=3, the N1-strongest
cells may include cells C1, C2 and C3, where cell C1 may be the
highest-ranked cell on carrier frequency f1, then cell C2 (the next
(e.g., second) highest-ranked cell), and then cell C3 (the next
highest-ranked cell after cell C2, or the third highest-ranked
cell). The UE may obtain the identification information (e.g.,
including PLMN ID #1, PLMN ID #2 and PLMN ID #3) of PLMNs from
cells C1, C2 and C3 in the broadcast system information of cells
C1, C2 and C3. The AS entity of the UE may report a list of
available/found PLMNs (e.g., including PLMN ID #1, PLMN ID #2 and
PLMN ID #3) to the NAS entity of the UE for PLMN selection. The NAS
entity of the UE may then select one of the reported
available/found PLMNs as the outcome of the PLMN selection
procedure. For example, PLMN #2 may be selected because it is
mapped to one PLMN in the list maintained or stored by the UE. In
one implementation, the UE may read the system information of the
N4-strongest cells on carrier frequency f1, wherein the signal
strength of N4-strongest cells may be above a threshold (e.g.,
fulfill the S criterion). The UE may obtain the identification
information of PLMNs from the system information broadcast by these
cells (e.g., N4-strongest cells). In some of the present
implementations, the value of N4 may be predefined (e.g., defined
by 3GPP specifications), preconfigured to the UE (e.g., stored in a
USIM and/or stored in a UICC), configured by cell(s) (e.g., via
system information and/or via dedicated signaling), or determined
based on UE implementation. In one implementation, if the UE may
find N0-strongest cells, where N0 is less than N1 in the
N1-strongest cell case or N0 is less than N4 in the N4-strongest
cell case, the UE may obtain the identification information of
PLMNs from the system information broadcast by these cells (e.g.,
N0-strongest cells). The AS entity of the UE may report the list of
available/found PLMNs (e.g., including the obtained identification
information of PLMNs) to the NAS entity of the UE for PLMN
selection. The NAS entity of the UE may then select one of the
reported available/found PLMNs as the outcome of the PLMN
selection. In some of the present implementations, if the UE cannot
select a PLMN, or if the UE cannot select a suitable cell, when the
UE performs the PLMN selection or cell (re)selection based on the
N0 or N1 configuration on a carrier frequency, the UE may
deprioritize this carrier frequency.
[0049] Once the PLMN is selected, the UE may perform the cell
selection procedure to search for a suitable cell to camp on. For
example, the UE may search for the N2-strongest cells on carrier
frequency f1, where N2 is a positive integer. In some of the
present implementations, the value of N2 may be predefined (e.g.,
defined by 3GPP specifications), preconfigured to the UE (e.g.,
stored in a USIM and/or stored in a UICC), configured by cell(s)
(e.g., via system information and/or via dedicated signaling), or
determined based on UE implementation. As shown in FIG. 2B, if
N2=3, the N2-strongest cells may include cells C1, C2 and C3. Cell
C1 may be the highest-ranked cell on carrier frequency f1, then
cell C2 (the next (e.g., second) highest-ranked cell), and then
cell C3 (the next highest-ranked cell after cell C2, or the third
highest-ranked cell).
[0050] As described above, each of cells C1, C2 and C3 may
broadcast the identification information of its corresponding
PLMN(s) in the system information (e.g., SIB1). Based on the system
information, the UE may know that cells C1, C2 and C3 belong to
PLMN #1, PLMN #2 and PLMN #3, respectively, which means the
N2-strongest cells on carrier frequency f1 belong to different
PLMNs. The UE may determine whether the suitable cell can be found
in the N2-strongest cells (e.g., cells C1, C2 and C3) on carrier
frequency f1, by checking whether these cells belong to the
selected PLMN or a PLMN that is indicated as being equivalent to a
registered PLMN of the UE. As illustrated in FIG. 2B, cell C2 may
be selected as the suitable cell for the UE to camp on because cell
C2 has the strongest/best received radio signal quality (e.g., RSRP
and/or RSRQ) among all cells (e.g., cells C2 and CK) belonging to
the selected PLMN (e.g., PLMN #2) on carrier frequency f1. In one
implementation, cell C2 may be selected as the suitable cell for
the UE to camp on because cell C2 is the highest-ranked cell among
cells (e.g., cells C2 and CK) belonging to the selected PLMN (e.g.,
PLMN #2).
[0051] It should be noted that even though the values of N1 and N2
are the same in the example implementation, in some of the present
implementations, the values of N1 and N2 may be independently
(pre)configured. In some other implementations, the value of N2 may
depend on that of N1. N2 may or may not have the same value as
N1.
[0052] In some of the present implementations, the value(s) of one
or more of N1, N2, N0, and N4 may be independently (pre)configured.
In some other implementations, the value of one of N1, N2, N0, and
N4 may depend on the value of another one of N1, N2, N0, and
N4.
[0053] FIG. 3 illustrates a flowchart for a method of performing
PLMN selection and cell (re)selection procedures on an unlicensed
spectrum, in accordance with an example implementation of the
present disclosure. As shown in FIG. 3, the method includes actions
302, 304, 306 and 308.
[0054] In action 302, a UE may perform a PLMN selection procedure
to select a PLMN.
[0055] In action 304, the UE may perform a cell selection procedure
to select a suitable cell to camp on. The suitable cell may belong
to the selected PLMN.
[0056] In action 306, the UE may determine whether the selected
suitable cell meets a cell reselection criterion (e.g., the R
criterion). The cell reselection criterion may be related to a
change in the measured metric value (e.g., the S criterion) of the
suitable cell. For example, once the signal quality of the selected
suitable cell is getting worse and deteriorates below a
predetermined threshold, the cell reselection criterion may be
fulfilled and trigger the UE to perform a cell reselection
procedure to find a new suitable cell, as illustrated in action
308. Conversely, in action 306, if the selected suitable cell does
not meet the cell reselection criterion, the UE may keep detecting
whether the current suitable cell meets the cell reselection
criterion, as illustrated in FIG. 3. It should be noted that when
the UE reselects the new suitable cell in action 308, the method
may proceed back to action 306, where the UE may continue to
determine whether the reselected suitable cell meets a cell
reselection criterion (e.g., the R criterion).
[0057] In one implementation, when the UE camps on a cell (e.g., a
selected suitable cell during cell (re)selection procedures), the
UE may regularly search for a better cell according to the cell
reselection criteria. If the UE finds a better cell, the UE may
select a better cell as the suitable cell to camp on. In one
implementation, the UE may reselect a new suitable cell if at least
one of the two conditions are met: (1) the new suitable cell is
better than the current serving/camped cell according to the cell
reselection criteria during a time interval, and (2) more than 1
second has elapsed since the UE began camping on the current
serving/camped cell.
[0058] FIG. 4A illustrates a flowchart for a cell reselection
procedure, in accordance with an example implementation of the
present disclosure.
[0059] In action 402, a UE may determine whether the highest-ranked
cell on a first carrier frequency belongs to the selected PLMN or
the registered PLMN (or the equivalent PLMN) of the UE.
[0060] If the outcome of action 402 is Yes, the UE may select the
highest-ranked cell as the new suitable cell in action 404. In this
case, the UE may switch from the original suitable cell to the new
suitable cell to camp on. Conversely, if the outcome of action 402
is No, the UE may prohibit the highest-ranked cell from being
selected as the new suitable cell for a period of time Ta in action
406. The length of Ta may be preconfigured in the UE or configured
by the cell(s) (e.g., via system information and/or via dedicated
signaling). In one implementation, the maximum value of Ta may be
300 seconds.
[0061] In action 408, when the highest-ranked cell is not selected
as the suitable cell by the UE to camp on, the UE may further
determine whether the next highest-ranked (e.g., the second
highest-ranked) cell on the first carrier frequency belongs to the
selected PLMN or the registered PLMN (or equivalent PLMN) of the
UE.
[0062] As described above, cells on a carrier frequency may be
ranked by their corresponding measured metric values. For example,
the highest-ranked cell and the next highest-ranked cell on the
first carrier frequency may be ranked by a received radio signal
quality (e.g., RSRP, RSRQ). In such a case, the next highest-ranked
cell may have a poorer received radio signal quality than the
highest-ranked cell.
[0063] In action 410, the UE may select the next highest-ranked
cell as the new suitable cell, when it is determined in action 408
that the next highest-ranked cell belongs to the selected PLMN or
the registered PLMN (or equivalent PLMN) of the UE. In this case,
the new suitable cell (belonging to the selected PLMN or a PLMN
that is indicated as being equivalent to a registered PLMN of the
UE) may be a non-highest-ranked (e.g., a lower-ranked) cell among
all cells on the first carrier frequency.
[0064] In action 412, the UE may determine that the next
highest-ranked cell is a non-suitable cell when the next
highest-ranked cell does not belong to the selected PLMN or the
registered PLMN (or equivalent PLMN) of the UE as determined in
action 408. In one implementation, the UE may prohibit the next
highest-ranked cell from being selected as the new suitable cell
for a period of time Tb when the next highest-ranked cell is
determined as a non-suitable cell. The length of Tb may be
preconfigured in the UE (e.g., stored in a USIM and/or stored in a
UICC) or configured by the cell(s) (e.g., via system information
and/or via dedicated signaling). In one implementation, the maximum
value of Tb may be 300 seconds.
[0065] In action 414, the UE may determine whether the total number
of non-suitable cells on the first carrier frequency reaches a
specific number. In the example implementation, the value of the
specific number may a positive integer. In some of the present
implementations, the specific number may be predefined (e.g.,
defined by 3GPP specifications), preconfigured to the UE (e.g.,
stored in a USIM and/or stored in a UICC), configured by cell(s)
(e.g., via system information and/or via dedicated signaling) or
determined based on UE implementation.
[0066] If the outcome of action 414 is Yes, the procedure may go to
node A, which continues to node A' in FIG. 5. If the outcome of
action 414 is No, the procedure may go back to action 408, in which
the UE may determine whether the next highest-ranked cell belongs
to the selected PLMN or the registered PLMN (or equivalent PLMN) of
the UE. In one implementation, the term "the next highest-ranked
cell" may refer to a cell with the rank after the rank of the cell
just being checked not to be selected.
[0067] In the example implementation, when the highest-ranked cell
is not selected as the suitable cell, the UE may iteratively
perform a process on the first carrier frequency, until the new
suitable cell is found on the first carrier frequency or a specific
number of cells on the first carrier frequency are determined as
non-suitable. As illustrated in FIG. 4, actions 408, 412 and 414
may be iteratively performed multiple times if the UE is
continuously unable to find a new suitable cell on the first
carrier frequency.
[0068] FIG. 4B illustrates a flowchart for a cell reselection
procedure, in accordance with another example implementation of the
present disclosure.
[0069] In action 420, a UE may determine whether the highest-ranked
cell among all non-prohibited cells on a first carrier frequency
belongs to the selected PLMN or the registered PLMN (or the
equivalent PLMN) of the UE. The non-prohibited cells may be the
cells that are not currently prohibited from being selected as the
new suitable cell for the UE to camp on. The prohibited cells may
be the cells that are currently prohibited from being selected
(e.g., via a cell-specific timer) as the new suitable cell for the
UE to camp on.
[0070] If the outcome of action 420 is Yes, the UE may select the
highest-ranked cell as the new suitable cell in action 422. In this
case, the UE may switch from the original suitable cell to the new
suitable cell to camp on. Conversely, if the outcome of action 420
is No, the UE may prohibit the highest-ranked cell from being
selected as the new suitable cell for a period of time (e.g., Ta)
in action 424. The length of Ta may be preconfigured in the UE
(e.g., stored in a USIM and/or stored in a UICC) or configured by
the cell(s) (e.g., via system information and/or via dedicated
signaling). In one implementation, the maximum value of Ta may be
300 seconds.
[0071] In action 426, the UE may determine that the highest-ranked
cell is a non-suitable cell because the highest-ranked cell does
not belong to the selected PLMN or the registered PLMN (or
equivalent PLMN) of the UE.
[0072] In action 428, the UE may determine whether the total number
of non-suitable cells on the first carrier frequency reaches a
specific number. In the example implementation, the value of the
specific number may be a positive integer. In some of the present
implementations, the specific number may be predefined (e.g.,
defined by 3GPP specifications), preconfigured to the UE (e.g.,
stored in a USIM and/or stored in a UICC), configured by cell(s)
(e.g., via system information and/or via dedicated signaling) or
determined based on UE implementation.
[0073] If the outcome of action 428 is Yes, the procedure may go to
node A, which continues to node A' in FIG. 5. If the outcome of
action 428 is No, the procedure may go back to action 420.
[0074] In some of the present implementations, action 428 may be
omitted. In such cases, once the highest-ranked cell is determined
as a non-suitable cell in action 426, the procedure may directly
proceed to node A. In some other implementations, actions 424, 426
and 428 may be omitted. In such cases, once the outcome of action
420 is No, the procedure may directly proceed to node A.
[0075] FIG. 5 illustrates a flowchart for a cell reselection
procedure performed when a UE cannot find a new suitable cell on
the first carrier frequency, in accordance with an example
implementation of the present disclosure. It should be noted that
although actions 502 and 504 are delineated as separate actions
represented as independent blocks in FIG. 5, these separately
delineated actions should not be construed as necessarily order
dependent. The order in which the actions are performed in FIG. 5
is not intended to be construed as a limitation, and any number of
the described blocks may be combined in any order to implement the
method, or an alternate method. Moreover, at least one of actions
502 and 504 may be omitted during the cell reselection procedure in
some of the present implementations.
[0076] In the example implementation, when the UE finds that the
total number of non-suitable cells on the first carrier frequency
reaches the specific number, the cell reselection procedure may
continue to node A' of FIG. 5. Then in action 502, the UE may
deprioritize the first carrier frequency in a set of carrier
frequencies for the cell reselection procedure for a period of time
(e.g., Tc). For example, the UE may search for the new suitable
cell on different carrier frequencies during the cell reselection
procedure, where each carrier frequency may be assigned with a
corresponding reselection priority. Once the first carrier
frequency is deprioritized (e.g., the reselection priority of the
first carrier frequency is reduced), the UE may select another
carrier frequency with a higher reselection priority than the first
carrier frequency, in order to search for the new suitable cell on
the selected carrier frequency during the later cell reselection
procedure. In one implementation, once the UE deprioritizes the
first carrier frequency in a set of carrier frequencies for the
cell reselection procedure, the UE may consider the first carrier
frequency to have the lowest priority among the set of carrier
frequencies. In some of the present implementations, the length of
Tc may be preconfigured in the UE or configured by the cell(s)
(e.g., via system information and/or via dedicated signaling). Tc
may or may not have the same value as Ta.
[0077] In action 504, the UE may search for the new suitable cell
on a second carrier frequency. In some of the present
implementations, the second carrier frequency may be an unlicensed
carrier frequency. In some other implementations, the second
carrier frequency may be a licensed carrier frequency. In one
implementation, after the UE deprioritizes the first carrier
frequency, the second carrier frequency may have the highest
priority among the set of carrier frequencies for cell reselection
procedure.
[0078] FIG. 6 is a schematic diagram illustrating a cell
reselection procedure, in accordance with an example implementation
of the present disclosure. As illustrated in FIG. 6, cells C5, C3
and C1 on carrier frequency f1 may be ranked by the received radio
signal quality (e.g., RSRP and/or RSRQ), from the strongest to the
weakest. Thus, cell C5 may be the highest-ranked cell on carrier
frequency f1, then cell C3, and then cell C1. It should be noted
that because the channel/network conditions may change over time,
the ranking of cells on carrier frequency f1 may be different as
compared with FIGS. 2A and 2B.
[0079] In the example implementation, cells C5, C3 and C1 may
broadcast the identification information (e.g., PLMN ID #5, PLMN ID
#3 and PLMN ID #1) of their corresponding PLMNs in the system
information (e.g., SIB1). Based on the system information, the UE
may know that cells C5, C3 and C1 belong to PLMN #5, PLMN #3 and
PLMN #1, respectively. If the selected/registered/equivalent PLMN
is PLMN #2, the UE may determine that cell C5 (the highest-ranked
cell on carrier frequency f1) is non-suitable because cell C5 does
not belong to PLMN #2. Based on the same reason, the UE may also
determine that cells C3 and C1 are non-suitable cells. Because the
UE cannot find the new suitable cell from the N3-strongest cells
(if N3=3) on carrier frequency f1, the UE may then search for the
new suitable cell on another carrier frequency f2, which may be a
licensed carrier frequency or an unlicensed carrier frequency.
[0080] On carrier frequency f2, the UE may follow the methods
illustrated in FIGS. 4 and 5 to continue the cell reselection
procedure. For example, the UE may determine whether the
highest-ranked cell on carrier frequency f2 belongs to the selected
PLMN or the PLMN that is indicated as being equivalent to the
registered PLMN of the UE. If the outcome of the determination is
Yes, the UE may select the highest-ranked cell on carrier frequency
f2 as the new suitable cell. Conversely, if the outcome of the
determination is No, the UE may prohibit the highest-ranked cell on
carrier frequency f2 from being selected as the new suitable cell
for a period of time (Td). In some of the present implementations,
Td and Ta may be independently (pre)configured, so the length of Td
may be independent of the length of Ta. In some other
implementations, the length of Td may depend on the length of Ta.
Td may or may not have the same length as Ta. In one
implementation, the maximum value of Td may be 300 seconds.
[0081] In some of the present implementations, when the
highest-ranked cell on carrier frequency f2 is not selected as the
new suitable cell, the UE may iteratively perform a process on
carrier frequency f2 until the new suitable cell is found from the
N3'-strongest cells on carrier frequency f2 or the total number of
non-suitable cells on carrier frequency f2 reaches N3', where N3'
is a positive integer. In some of the present implementations, the
value of N3' may be predefined (e.g., defined by 3GPP
specifications), preconfigured to the UE (e.g., stored in a USIM
and/or stored in a UICC), configured by cell(s) (e.g., via system
information and/or via dedicated signaling), or determined based on
UE implementation. In some of the present implementations, the
value of N3' may be independent of the value of N3. In some other
implementations, the value of N3' may depend on the value of N3.
N3' may or may not have the same value as N3. In one
implementation, the UE may not read the system information from all
of the N3'-strongest cells before the UE finds and camps on the new
suitable cell on carrier frequency f2. Once the UE finds and camps
on the new suitable cell on carrier frequency f2, the UE may not
further read the system information from the next highest-ranked
cell with the rank after that of the new suitable cell. Once the UE
finds and camps on the new suitable cell on carrier frequency f2,
the UE may not further measure the received radio signal quality of
the remaining cells on carrier frequency f2 for this cell
reselection procedure. Once the UE finds and camps on the new
suitable cell on carrier frequency f2, the UE may not further rank
the remaining cells on carrier frequency f2 for this cell
reselection procedure.
[0082] As illustrated FIG. 6, if N3'=3, the N3'-strongest cells may
include cells C4, C6 and C2, where cell C4 may be the
highest-ranked cell on carrier frequency f2, then cell C6, and then
cell C2. Cells C4, C6 and C2 may broadcast the identification
information (e.g., PLMN ID #4, PLMN ID #6 and PLMN ID #2) of their
corresponding PLMNs in the system information (e.g., SIB1). Based
on the system information, the UE may know that cells C4, C6 and C2
belong to PLMN #4, PLMN #6 and PLMN #2, respectively, and
(re)select cell C2 as a new suitable cell because cell C2 belongs
to the selected PLMN #2.
[0083] FIG. 7 is a schematic diagram illustrating a message flow
between the AS entity of the UE and the NAS entity of a UE, in
accordance with an example implementation of the present
disclosure.
[0084] As illustrated in FIG. 7, the NAS entity 73 of the UE may
provide a message to the AS entity 71 of the UE in action 702. The
message may indicate which of one or more PLMN types are supported
by the UE. Based on the message, the AS entity 71 may or may not
modify the list of available PLMNs to be reported to the NAS entity
73. For example, the AS entity 71 may filter out some PLMNs, with
PLMN types not supported by the UE, from the list of PLMNs to be
reported to the NAS entity 73. In some of the present
implementations, the one or more PLMN types may include a public
PLMN type, a private PLMN type, and a public and private PLMN type.
In one implementation, if the NAS entity 73 of the UE does not
provide a message to the AS entity 71 of the UE, it means that the
UE supports (or needs) to select a public PLMN as the outcome of
PLMN selection. In one implementation, if the NAS entity 73 of the
UE provides a message to the AS entity 71 of the UE, and if the
message includes a first indicator corresponding to the private
PLMN type, it means that the UE supports (or needs) a private PLMN
as the outcome of PLMN selection. In one implementation, if the NAS
entity 73 of the UE provides a message to the AS entity 71 of the
UE, and if the message includes a second indicator corresponding to
the public and private PLMN types, it means that the UE supports
(or needs) a public or private PLMN as the outcome of PLMN
selection.
[0085] As mentioned above, multiple networks (e.g., PLMNs) may
operate on unlicensed or licensed spectrums. In addition, multiple
networks (e.g., PLMNs) may share the same unlicensed carrier or the
same licensed carrier. Each network may be public, private or both.
Public networks (e.g., public PLMNs) may (but not limited to) be
provided by operators or virtual operators, which may provide radio
services to the public subscribers. The public networks may own one
or more licensed spectrums and support the radio access technology
on the licensed spectrum(s) as well. The public networks may
support the radio access technology on unlicensed spectrums as
well. On the other hand, private networks (e.g., private PLMNs) may
(but not limited to) be provided by micro-operators, factories, or
enterprises, which may provide radio services to their private
users (e.g., employees or machines). The private networks may
support the radio access technology on the unlicensed spectrum(s).
If the private PLMNs own a licensed spectrum, the corresponding
private networks may support the radio access technology on the
licensed spectrum as well.
[0086] It should be noted that even though the term "public PLMN"
may be used in some of the present implementations, such a term may
be replaced by another term "public network" because the techniques
described therein are not intended to be limited to the public
PLMN(s) and may be applicable to other types of public network(s).
Similarly, even though the term "private PLMN" may be used in some
of the present implementations, such a term may be replaced by
another term such as "private network" or "non-public network"
(NPN) because the techniques described therein are not intended to
be limited to the private PLMN(s) and may be applicable to other
types of private/non-public network(s). In one implementation, the
private network scenario may be a Stand-alone Non-Public Network
(SNPN), i.e., operated by an NPN operator and not relying on
network functions provided by a (public) PLMN. In another
implementation, the NPN scenario may be a Public Network Integrated
NPN (PNI-NPN), i.e., a non-public network deployed with the support
of a (public) PLMN. The SNPN(s) may be identified by PLMN ID and/or
Network ID (NID) broadcast in SIB1 of a cell supporting SNPN. The
PNI-NPN may be identified by PLMN ID and/or Cell Access Group (CAG)
ID broadcast in SIB1 of a cell supporting PNI-NPN. The
identification information of an SNPN (e.g., an SNPN ID) may
include a PLMN ID and/or an NID. The identification information of
a PNI-NPN (e.g., a PNI-NPN ID) may include a PLMN ID and/or a CAG
ID. Each of the PLMN ID, the SNPN ID, and the PNI-NPN ID may be
referred to as a PLMN-related ID. In some of the present
implementations, the PLMN-related ID may be included in the
identification information of a PLMN.
[0087] In some of the present implementations, public PLMNs and
private PLMNs may support several deployment scenarios. For
example, the deployment scenarios may include the carrier
aggregation between the licensed band (e.g., NR, for the Primary
Cell (PCell)) and the unlicensed band (e.g., NR-U, for the
Secondary Cell (SCell)), wherein the unlicensed SCell may have both
DL and UL, or DL-only; the dual connectivity (or
multi-connectivity) between the radio access technology on the
licensed band (e.g., LTE, NR, for the PCell) and the radio access
technology on the unlicensed band (e.g., NR-U, for the Primary
Secondary Cell (PSCell)); the dual connectivity (or
multi-connectivity) between the licensed band (e.g., LTE, for the
PCell) and the stand-alone radio access technology (e.g.,
stand-alone NR-U) on the unlicensed band; an NR cell with DL in
unlicensed band and UL in licensed band; and the stand-alone
unlicensed radio access technology (e.g., stand-alone NR-U). In
some of the present implementations, private PLMNs may mainly
support (but not limited to) the stand-alone unlicensed radio
access technology (e.g., stand-alone NR-U).
[0088] During the PLMN selection procedure, the AS entity of the UE
may report available PLMNs to the NAS entity of the UE on request
from the NAS entity of the UE or automatically in some of the
present implementations. In some of the present implementations,
the NAS entity of the UE may inform the AS entity of the UE of
which PLMN type (e.g., public, private, both) the UE supports (as
illustrated in FIG. 7).
[0089] In some of the present implementations, the AS entity of the
UE may be preconfigured with the information of which PLMN type
(e.g., public, private, both) the UE supports. In some of the
present implementations, if the UE supports pubic PLMNs only, the
AS entity of the UE may report the available public PLMNs to the
NAS entity of the UE. In some of the present implementations, if
the UE supports the private PLMNs only, the AS entity of the UE may
report the available private PLMNs to the NAS entity of the UE. In
some of the present implementations, if the UE supports pubic PLMNs
and private PLMNs, the AS entity of the UE may report the available
public PLMNs and/or private PLMNs to the NAS entity of the UE.
[0090] In some of the present implementations, the public PLMNs and
the private PLMNs may use the same Mobile Country Code (MCC) but
different Mobile Network Codes (MNCs). In some of the present
implementations, if multiple PLMNs share the same MCC, the cell may
transmit both the MCC and the MNC of one of the PLMNs (e.g., via
system information and/or via dedicated signaling), and transmit
only the MNCs (with an absence of the MCC) of the other PLMNs.
[0091] In some of the present implementations, a cell may broadcast
the identification information of one or more PLMNs operating other
cells on the same carrier frequency (e.g., on an unlicensed carrier
frequency). For example, the one or more PLMNs may be called as
"neighboring PLMN(s)." The UE may read the identification
information broadcast by the cell (e.g., in SIB1 or other System
Information (SI)) and obtain the PLMN ID(s) of the neighboring
PLMN(s) that operate cells on the same carrier frequency. The AS
entity of the UE may report the found PLMN ID(s), including the
identification information of PLMNs operating this cell and PLMNs
operating neighboring cells on the same carrier frequency, to the
NAS entity of the UE. The NAS entity of the UE may then select a
PLMN as an outcome of the PLMN selection procedure based on the
reported PLMN ID(s).
[0092] In some of the present implementations, the system
information from the cell(s) on a carrier frequency (e.g., licensed
carrier frequency, unlicensed carrier frequency) may include PLMN
type information that indicates at least one PLMN type (e.g.,
public, private, or both) associated with the cells. For example, a
cell on an unlicensed spectrum may broadcast an indicator to
indicate that the cell is shared by public PLMNs, private PLMNs, or
both of the public and private PLMNs. In some of the present
implementations, each PLMN ID broadcast by the cell may be
accompanied by an indicator to indicate the PLMN type associated
with the corresponding PLMN ID. For example, the cell may broadcast
several PLMN lists. One PLMN list may include the PLMN IDs of
public PLMNs, one PLMN list may include the PLMN IDs of private
PLMNs, and one PLMN list may include the PLMN IDs of both public
and private PLMNs.
[0093] In some of the present implementations, the cell may
broadcast the indicator(s) and the identification information of
PLMN(s) (e.g., PLMN ID list(s)) via the SIB1 or other SI. If there
is no additional indicator broadcasted by the cell operating on the
unlicensed spectrum, the UE may, by default, treat the PLMNs
identified by the broadcast identification information of PLMN(s)
(e.g., PLMN ID list) as public PLMNs. In some of the present
implementations, if the UE supports public PLMNs only, the AS
entity of the UE may treat the public PLMN IDs broadcast by the
cell as the candidate available PLMNs. In some of the present
implementations, if the UE supports private PLMNs only, the AS
entity of the UE may treat the private PLMN IDs (e.g., PLMN IDs
and/or NIDs, PLMN IDs and/or CAG IDs) broadcast by the cell as the
candidate available PLMNs. In some of the present implementations,
if the UE supports both public PLMNs and private PLMNs, the AS
entity of the UE may treat both the public PLMN IDs and the private
PLMN IDs broadcast by the cell as the candidate available PLMNs. In
some of the present implementations, the AS entity of the UE may
select the available PLMNs from the candidate available PLMNs based
on a predefined rule. For example, if the signal quality of a cell
broadcasting the identification information of one or more
candidate available PLMNs fulfills a high-quality criterion, the
one or more candidate available PLMNs may be selected as the
available PLMN(s). The AS entity of the UE may report the available
PLMN(s) to the NAS entity of the UE for PLMN selection.
[0094] In some of the present implementations, on each unlicensed
carrier frequency, the UE may search for the N-strongest cells
(e.g., the N1-strongest cells, the N2-strongest cells, the
N3-strongest cells, or the N3'-strongest cells as illustrated in
FIGS. 2A, 2B and 6) and read their system information, in order to
find out which PLMN(s) the cells belong to Taking FIG. 2A as an
example, where N=N1=3, cells C1, C2 and C3 are the N1-strongest
cells that meet the high-quality criterion on carrier frequency f1.
According to the system information of cells C1, C2 and C3, the UE
may know that cells C1, C2 and C3 belong to PLMN #1, PLMN #2 and
PLMN #3, respectively. In some of the present implementations, on
each unlicensed carrier, the UE may search for at most N-strongest
cells and read their system information, in order to find out which
PLMN(s) the cells belong to.
[0095] In some of the present implementations, the value of N may
be predefined (e.g., defined by 3GPP specifications), preconfigured
to the UE (e.g., stored in a USIM and/or stored in a UICC), or
configured by cell(s) (e.g., via system information and/or via
dedicated signaling), determined based on UE implementation.
[0096] In some of the present implementations, the UE may search
for the N-strongest cells which supports the UE's PLMN type (e.g.,
public, private, both), and read their system information. For
example, if the UE supports public PLMNs, the UE may search for the
N-strongest cells which support public PLMNs and read their system
information. In such a case, the searched maximum N strongest cells
support the UE's PLMN type (e.g., public, private, both).
[0097] In some of the present implementations, the UE may search
for the N-strongest cells regardless of their supporting PLMN types
and read their system information. In such a case, the searched
N-strongest cells may possibly not support the UE's PLMN type. In
some of the present implementations, if the UE cannot search for
the N-strongest cells on the unlicensed carrier frequency, the UE
may turn to search for the X-strongest cells on the unlicensed
carrier frequency and read their system information, where X is a
positive integer smaller than N. The value of X may be
preconfigured or left for UE implementations.
[0098] In some of the present implementations, the search for PLMNs
may be stopped/modified (e.g., change the N or X value) on request
from the NAS entity of the UE. The UE may optimize the PLMN search
upon the N-strongest cells and/or X-strongest cells by using the
stored information (e.g., information of carrier frequencies) and
optionally also the information of the cell parameters from
previously received measurement control information elements.
[0099] In some of the present implementations, the UE may measure
the channel occupancy ratio of all carrier frequencies. The UE may
select the carrier frequency with the lowest channel occupancy
ratio and read the system information of cells on the selected
carrier frequency.
[0100] If the UE reads one or more PLMN IDs in each of the
N-strongest cells, each found PLMN may be reported to the NAS
entity of the UE as the high quality PLMN(s). In some of the
present implementations, if the UE reads one or more PLMN IDs in
each of the N-strongest cells, each found PLMN, which belongs to
the PLMN type supported by the UE (e.g., public, private, or both),
may be reported to the NAS entity of the UE as the high quality
PLMN(s). In such cases, the found PLMN(s) to be reported to the NAS
entity of the UE may be regarded as the available PLMN(s) reported
by the AS entity of the UE to NAS entity of the UE.
[0101] In some of the present implementations, the high-quality
criterion for finding the N-strongest cells may be fulfilled if the
measured metric value of a cell is greater than, or equal to, a
threshold value (e.g., -110 dBm). The measured metric value may be
at least one of a RSRP value, a RSRQ value, a Received Signal
Strength Indicator (RSSI) value, a Signal to
Interference-plus-Noise Ratio (SINR) value, and a channel occupancy
ratio value. The threshold value may be predefined, preconfigured,
or configured by the cell through the system information (e.g., via
the SIB1 or other SI) or dedicated signaling (e.g., via RRC
messages). For example, the measured RSRP value may be greater than
or equal to a threshold value, e.g., -110 dBm. If the system
information and the dedicated signaling are adopted, the threshold
value may be stored by the UE and used in a later PLMN selection
procedure. For example, the UE may use the stored threshold value
given by the SI or dedicated signaling for the PLMN selection.
Whether a cell is "strong" or not may depend on the measured metric
value of the cell. For example, if the RSRP value is used as the
measured metric value, the UE may create a cell list for an
unlicensed carrier frequency according to the order of RSRP values
of the cells on the unlicensed carrier frequency. For example, the
cell list may include cell IDs (or other identification information
of the cells) which are ordered by their corresponding cells'
measured metric values, from the highest measured metric value to
the lowest measured metric value. In some of the present
implementations, the UE may measure an unlicensed carrier frequency
or a licensed carrier frequency for a time period (Tm). The value
of Tm may be predefined, preconfigured, or depend on UE
implementation. If Tm is not configured to the UE, a default value
for Tm may be adopted. In some of the present implementations, Tm
may be dynamically configured by the cell via the system
information (e.g., the SIB1 or other SI) or the dedicated signaling
(e.g., via RRC messages) to the UE. In some of the present
implementations, the measured metric value may be obtained from
measurements during the time period Tm. In some of the present
implementations, the measured metric value may be obtained by
averaging a set of measured metric values sampled in the time
period Tm.
[0102] In some of the present implementations, if the N-strongest
cells fulfill the high-quality criterion, the AS entity of the UE
may report the identification information of PLMNs (e.g., PLMN
ID(s), PLMN ID(s) and/or NID(s), PLMN ID(s) and/or CAG ID(s)) found
from the broadcast system information by the N-strongest cells to
the NAS entity of the UE, without reporting the measured metric
value(s). In some of the present implementations, when the
N-strongest cells fulfill the high-quality criterion, the AS entity
of the UE may report the identification information of PLMNs (e.g.,
PLMN ID(s), PLMN ID(s) and/or NID(s), PLMN ID(s) and/or CAG ID(s))
found from the broadcast system information by the N-strongest
cells and the measured metric values of the N-strongest cells to
the NAS entity of the UE. In some of the present implementations,
when the N-strongest cells do not fulfill the high-quality
criterion but the UE has detected the identification information of
PLMNs (e.g., PLMN ID(s), PLMN ID(s) and/or NID(s), PLMN ID(s)
and/or CAG ID(s)) from the broadcast system information by the
N-strongest cells, the AS entity of the UE may report the detected
identification information of PLMNs and the measured metric values
of the N-strongest cells to the NAS entity of the UE. In some of
the present implementations, the measured metric value of each PLMN
found on the same N-strongest cells may be the same. In some of the
present implementations, the measured metric value of each PLMN
found on the N-strongest cells that does not fulfill the
high-quality criterion may be the same.
[0103] In some of the present implementations, if the number of
cells fulfilling the high-quality criterion is greater than, or
equal to, 1 but less than N, the AS entity of the UE may report the
identification information of PLMNs found on the cells fulfilling
the high-quality criterion to the NAS entity of the UE. In some of
the present implementations, if the number of cells fulfilling the
high-quality criterion is greater than, or equal to, 1 but less
than N, the AS entity of the UE may report the identification
information of PLMNs found on the cells not fulfilling the
high-quality criterion, and the measured metric value of each PLMN
found on the cells not fulfilling the high-quality criterion, to
the NAS entity of the UE. In some of the present implementations,
if the number of cells fulfilling the high-quality criterion is
zero, the AS entity of the UE may report the identification
information of PLMNs found on the N-strongest cells together with
the corresponding measured metrics of the N-strongest cells. In
some of the present implementations, if the ranking of the measured
metric value of a cell is in the top N but the UE cannot read any
PLMN ID from this cell, the UE may not consider such a cell as one
of the N-strongest cells. In some of the present implementations,
the UE may then store the information (e.g., the relative cell ID)
of the cell and take it into account for a further cell
(re)selection in which the cell may be given a lower priority to be
selected as a suitable cell than other cells. The UE may remove the
information (e.g., the relative cell ID) of the cell after the cell
selection procedure, after a cell reselection procedure, or after a
period of time.
[0104] In some of the present implementations, the AS entity of the
UE may select a PLMN as the outcome of the PLMN selection
procedure. This type of PLMN selection procedure may be referred to
as a procedure of PLMN selection by UE AS.
[0105] In some of the present implementations, during the procedure
of PLMN selection by UE AS, the NAS entity of the UE may provide a
potential PLMN list to the AS entity of the UE. The potential PLMN
list may include at least one PLMN-related ID. In some
implementations, the PLMN-related ID(s) may be PLMN ID(s), SNPN
ID(s), or PNI-NPN ID(s). The SNPN ID(s) may include PLMN ID(s)
and/or NID(s). The PNI-NPN ID(s) may include PLMN ID(s) and/or CAG
ID(s).
[0106] The AS entity of the UE may select one or more PLMN-related
IDs from the potential PLMN list and report the selected
PLMN-related ID(s) in a selected PLMN list to the NAS entity of the
UE. In some of the present implementations, the AS entity of the UE
may inform the NAS entity of the UE of the selected PLMN-related
ID(s) by reporting the index(ices) of the potential PLMN list(s).
In some of the present implementations, if the AS entity of the UE
cannot select any PLMN-related ID from the potential PLMN list, the
AS entity of the UE may report a default value to the NAS entity of
the UE to indicate the selected PLMN. In some of the present
implementations, the selected PLMN's PLMN-related ID may be in the
beginning (or in the end) of the selected PLMN list.
[0107] In some of the present implementations, the search for PLMNs
may be stopped once the AS entity of the UE has selected a PLMN. In
some of the present implementations, the search for PLMNs may be
stopped once the AS entity of the UE has found the N-strongest
cells. In some of the present implementations, the PLMN IDs
broadcast by the N-strongest cells may not match the potential PLMN
list. In some of the present implementations, one or more PLMN IDs
broadcast by the N-strongest cells may match the potential PLMN
list and the AS entity of the UE may select the PLMN(s) which
matches the potential PLMN list. In some of the present
implementations, the search for PLMNs may be stopped once the AS
entity of the UE has found all cells that fulfill the high-quality
criterion or the N-strongest cells that fulfill the high-quality
criterion.
[0108] In some of the present implementations, the PLMN-related ID
of the selected PLMN by the AS entity of the UE may be broadcast by
one or more of the N-strongest cells via the SIB1 or other SI. In
such a case, the N-strongest cells may fulfill the high-quality
criterion. In some of the present implementations, the AS entity of
the UE may select the PLMN with its PLMN-related ID being broadcast
by the most cells that fulfill the high-quality criterion. These
cells may be operated in the intra-frequency or in the
inter-frequency. In some of the present implementations, the AS
entity of the UE may select the PLMN with its PLMN-related ID being
broadcast by the most cells for which the UE has been able to read
the PLMN-related IDs. In some of the present implementations, the
AS entity of the UE may select the PLMN with its PLMN-related ID
being broadcast by the cell which has the strongest measured metric
value among cells broadcasting the UE's potential PLMN list.
[0109] In some of the present implementations, if the NAS entity of
the UE verifies/approves the PLMN selected by the AS entity of the
UE, the NAS entity of the UE may provide a positive indicator to
the AS entity of the UE. After receiving the positive indicator,
the AS entity of the UE may perform the cell selection procedure to
select a suitable cell belonging to the selected PLMN to camp on.
Conversely, if the NAS entity of the UE fails to verify (or
rejects) the selected PLMN, the NAS entity of the UE may provide a
negative indicator to the AS entity of the UE. After receiving the
negative indicator, the AS entity of the UE may trigger the PLMN
selection procedure. In some of the present implementations, after
receiving the negative indicator, the AS entity of the UE may bar
the reported PLMN for a period of time to avoid selecting it again.
In some of the present implementations, after receiving the
negative indicator, the AS entity of the UE may report another PLMN
in the selected PLMN list to the NAS entity of the UE. If no other
PLMN is in the selected PLMN list, the AS entity of the UE may
trigger the PLMN selection procedure. In some of the present
implementations, if the NAS entity of the UE fails to verify (or
rejects) the selected PLMN, the NAS entity of the UE may select a
PLMN from the selected PLMN list by itself. In some of the present
implementations, the NAS entity of the UE may indicate to the AS
entity of the UE which PLMN is selected, if the NAS entity of the
UE selects the PLMN.
[0110] In some of the present implementations, the AS entity of the
UE may select a PLMN and report a selected PLMN list to the NAS
entity of the UE. The selected PLMN list may include the selected
PLMN's identification information (e.g., the PLMN-related ID(s) of
the selected PLMN(s)). For example, the PLMN-related ID of the
selected PLMN may be, by default, arranged in the first or last
entry of the selected PLMN list. In some of the present
implementations, an indicator may be used in the selected PLMN list
to mark the selected PLMN. In some of the present implementations,
once the AS entity of the UE confirms that the selected PLMN has
been verified by the NAS entity of the UE (e.g., the AS entity of
the UE reports a selected PLMN to the NAS entity of the UE, and
then receives a positive indicator from the NAS entity of the UE),
the UE may perform the cell selection procedure to select a
suitable cell belonging to the selected PLMN to camp on. In some of
the present implementations, the suitable cell may fulfill the
high-quality criterion. In some of the present implementations, if
the cell where the UE receives the PLMN ID of the selected PLMN
does not fulfill the high-quality criterion, the UE may perform the
cell (re)selection procedure to find another cell as the suitable
cell (e.g., the UE does not directly select such cell as the
suitable cell).
[0111] After PLMN selection, the UE may perform a cell selection
procedure to find out a suitable cell belonging to the selected
PLMN on a carrier frequency. In some of the present
implementations, the UE may perform measurements for cell selection
and reselection purposes.
[0112] The NAS entity of the UE may control the RAT(s). For
example, during the cell selection procedure, the NAS entity of the
UE may request the AS entity of the UE to perform measurements on
an unlicensed spectrum (e.g., including one or more unlicensed
carrier frequencies) for the unlicensed RAT(s) (e.g., NR-U). The
NAS entity of the UE may indicate the RAT(s) associated with the
selected PLMN (e.g., equivalent PLMN(s) or registered PLMNs) to the
AS entity of the UE. In some of the present implementations, the
NAS entity of the UE may maintain at least one of a list of
forbidden registration area(s) and a list of equivalent/registered
PLMN(s). In some of the present implementations, the NAS entity of
the UE may define the range of forbidden registration area(s) by
GPS coordination. The UE may select a suitable cell based on the
RRC_IDLE or RRC_INACTIVE state measurements and the cell selection
criteria. In some of the present implementations, the UE may
utilize the RRC_CONNECTED state measurements for cell
(re)selection.
[0113] In unlicensed carrier frequencies, because multiple PLMNs
may possibly use the same carrier frequency without any
coordination, the best cell found by a UE on an unlicensed carrier
frequency may not belong the selected/registered/equivalent PLMN.
In some of the present implementations, the UE may select a
non-best cell on the unlicensed carrier frequency as a suitable
cell to camp on, if the best cell does not belong to the
selected/registered/equivalent PLMN. In some of the present
implementations, the non-best cell may have a better received radio
signal quality than other cells belonging to the
selected/registered/equivalent PLMN. Taking FIG. 2B as an example,
the best cell C1 does not belong to the selected PLMN #2, so the UE
may skip cell C1 and select the next-best cell C2 (which belongs to
the selected PLMN #2) as the suitable cell to camp on. In addition,
cell C2 may have a better received radio signal quality than other
cells belonging to the selected PLMN #2 (e.g., cell CK).
[0114] In some of the present implementations, for an initial cell
selection, the UE may scan all Radio Frequency (RF) channels in the
unlicensed bands according to its capabilities to find a suitable
cell, if the UE is indicated to utilize the unlicensed RAT(s). On
each carrier frequency within an unlicensed spectrum, the UE may
read the system information of the cells and search for the
strongest cell belonging to the UE's selected/registered/equivalent
PLMN. That is, among all cells in each carrier frequency which
broadcast the identification information of the UE's
selected/registered/equivalent PLMN, the UE may find the strongest
one as the suitable cell. Conversely, among all cells in each
carrier frequency, a cell (e.g., cell C1 illustrated in FIG. 2B)
that does not broadcast the selected/registered/equivalent PLMN's
identification information may not be selected as the suitable
cell, even if the cell has a better received radio signal quality
than other cells.
[0115] In some of the present implementations, the UE may be
configured with a threshold value. The threshold value may be
preconfigured or broadcast by the cells. In some of the present
implementations, the threshold value may be a cell-specific
threshold value that is broadcast by each cell. Such a
cell-specific threshold value may be applied to the corresponding
cell to determine whether the cell has a good signal quality to be
selected as a suitable cell. For example, on each carrier
frequency, the UE may search for the cells with their measured
metric values above the threshold value. Among the searched cells,
the UE may find a suitable cell. As illustrated in FIG. 2B, each of
cells C1, C2, C3 on carrier frequency f1 may have a measured metric
value above the threshold value. Among cells C1, C2, C3, the UE may
consider cell C2 as the suitable cell because it belongs to the
selected PLMN #2.
[0116] In some of the present implementations, the UE may require
the information of carrier frequencies, which the UE may receive
from measurement control information elements of a camped/serving
cell and/or from the system information of a
camped/serving/detected cell, for performing cell (re)selection
procedures. In some of the present implementations, the UE may
require the information of cell parameters, which the UE may
receive from measurement control information elements of a
camped/serving cell and/or from the system information of a
camped/serving/detected cells, for performing cell (re)selection
procedures. In some of the present implementations, if a cell does
not broadcast the threshold value, the UE may always treat the cell
as a suitable cell. For example, the UE may assume that the
threshold value for the cell is negative infinity. In some of the
present implementations, if a cell does not broadcast the threshold
value, the UE may use a default threshold value to perform the
comparison between the received signal quality and the threshold
value. In some of the present implementations, the threshold value
broadcast by a cell may be set to positive infinity when the cell
bars all UEs. In some of the present implementations, the UE may
set the threshold value for a cell to be positive infinity when the
UE bars the corresponding cell.
[0117] In some of the present implementations, on each carrier
frequency, the UE may search for the cells that satisfy the
following two conditions: (1) such cells belong to the UE's
selected/registered/equivalent PLMN, and (2) the measured metric
values of such cells are above a threshold value. Among the
searched cells on each frequency, the UE may select the strongest
one (e.g., with the best measured metric value) as the suitable
cell. In some of the present implementations, once the UE finds a
cell that satisfies the above two conditions, the UE may directly
select the cell as the suitable cell if the cell is not barred to
the UE.
[0118] In some of the present implementations, the UE may use the
cell selection criterion S to find the suitable cell. In some of
the present implementations, the cell selection criterion S may be
different between a licensed spectrum and an unlicensed spectrum.
For example, for a cell selection procedure on the licensed
spectrum, the cell selection criterion S in a normal coverage may
be fulfilled when:
Srxlev>0 and Squal>0,
where:
Srxlev=Q.sub.rxlevmeas-(Q.sub.rxlevmin+Q.sub.rxlevminoffset)-P.sub.compe-
nsation-Qoffset.sub.temp, and
Squal=Q.sub.qualmeas-(Q.sub.qualmin-Q.sub.qualminoffset)-Qoffset.sub.tem-
p
where:
TABLE-US-00001 Srxlev Cell selection Receive (RX) level value (dB)
Squal Cell selection quality value (dB) Qoffset.sub.temp Offset
temporarily applied to a cell (dB) Q.sub.rxlevmeas Measured cell RX
level value (RSRP) Q.sub.qualmeas Measured cell quality value
(RSRQ) Q.sub.rxlevmin Minimum required RX level in the cell (dB m).
If the UE supports Supplementary Uplink (SUL) frequency for this
cell, Qrxlevmin is obtained from q-RxLevMin- sul, if present, in
SIB1, SIB2 and SIB4, additionally, if Q.sub.rxlevminoffsetcellSUL
is present in SIB3 and SIB4 for the concerned cell, this cell
specific offset is added to the corresponding Qrxlevmin to achieve
the required minimum RX level in the concerned cell; else Qrxlevmin
is obtained from q-RxLevMin in SIB1, SIB2 and SIB4, additionally,
if Q.sub.rxlevminoffsetcell is present in SIB3 and SIB4 for the
concerned cell, this cell specific offset is added to the
corresponding Qrxlevmin to achieve the required minimum RX level in
the concerned cell. Q.sub.qualmin Minimum required quality level in
the cell (dB). Additionally, if Q.sub.qualminoffsetcell is signaled
for the concerned cell, this cell specific offset is added to
achieve the required minimum quality level in the concerned cell.
Q.sub.rxlevminoffset Offset to the signaled Q.sub.rxlevmin taken
into account in the Srxlev evaluation as a result of a periodic
search for a higher priority PLMN while camped normally in a
Visited PLMN (VPLMN) Q.sub.qualminoffset Offset to the signaled
Q.sub.qualmin taken into account in the Squal evaluation as a
result of a periodic search for a higher priority PLMN while camped
normally in a VPLMN P.sub.compensation If the UE supports the
additionalPmax in the NS-PmaxList, if present, in SIB1, SIB2 and
SIB4: max(P.sub.EMAX1 - P.sub.PowerClass, 0) - (min(P.sub.EMAX2,
P.sub.PowerClass) - min(P.sub.EMAX1, P.sub.PowerClass)) (dB); else:
max(P.sub.EMAX1 - P.sub.PowerClass, 0) (dB) P.sub.EMAX1, Maximum TX
power level of a UE may use when transmitting on the uplink in
P.sub.EMAX2 the cell (dBm) defined as P.sub.EMAX. If UE supports
SUL frequency for this cell, P.sub.EMAX1 and P.sub.EMAX2 are
obtained from the p-Max for SUL in SIB1 and NR-NS- PmaxList for SUL
respectively in SIB1, SIB2 and SIB4, else P.sub.EMAX1 and
P.sub.EMAX2 are obtained from the p-Max and NR-NS-PmaxList
respectively in SIB1, SIB2 and SIB4 for normal UL. P.sub.PowerClass
Maximum RF output power of the UE (dBm) according to the UE power
class.
[0119] In some of the present implementations, other criteria may
be applied to the unlicensed spectrum operations. For example, an
SINR value may be a measured metric value. The UE may compare the
signal strength from a cell with the interference caused from other
cells. In some of the present implementations, the SINR value may
be defined by a Synchronization Signal (SS)-SINR (SS-SINR) value.
For example, the SS-SINR value may be defined as (but not limited
to) the linear average over the power contribution (in [W]) of the
resource elements carrying (secondary) SSs divided by the linear
average of the noise and interference power contribution (in [W])
over the resource elements carrying (secondary) SSs within the same
frequency bandwidth. In some of the present implementations, the
time resource(s) for measuring the SS-SINR value may be confined
within an SS/Physical Broadcast Channel (PBCH) Block Measurement
Time Configuration (SMTC) window duration. The UE may receive the
SMTC for measuring a cell via dedicated signaling or system
information from this cell or other cells.
[0120] In some of the present implementations, the SINR value of a
cell may be greater than, or equal to, a threshold (e.g.,
S.sub.SINR>0, S.sub.SINR=Q.sub.SINR-Q.sub.SINR_th+R.sub.SINR).
S.sub.SINR may be the S criterion associated to the SINR value.
Q.sub.SINR may be the measured cell RX SINR value (dB).
Q.sub.SINR_th may be the threshold associated to the SINR value.
R.sub.SINR may be the remainder items if necessary. Each item may
either be broadcast by the cell to the UE, be unicast via dedicated
signaling by the cell, or be preconfigured to the UE (e.g., stored
in a USIM and/or stored in a UICC). In some of the present
implementations, R.sub.SINR may be zero. Q.sub.SINR_th may be
preconfigured or broadcast in the Master Information Block (MIB) or
SIB1 from the cell. Q.sub.SINR_th may be cell-specific or unique
for the system. For example, if Q.sub.SINR_th is cell-specific, it
may be applied to the cell which broadcasts the Q.sub.SINR_th
value.
[0121] For cell selection procedures under multi-beam operations,
the average SINR among beams of a cell may be considered. For
example, the beam-average SINR of a cell may be greater than, or
equal to, a threshold (e.g., S.sub.SINR_av>0,
S.sub.SINR_av=Q.sub.SINR_av-Q.sub.SINR_th_av+R.sub.SINR_av).
S.sub.SINR_av may be the S criterion associated to the beam-average
SINR. Q.sub.SINR_av may be the beam-average SINR of a cell.
Q.sub.SINR_th_av may be the threshold associated with the
beam-average SINR. R.sub.SINR_av may be the remainder items if
necessary. Each item may either be broadcast by the cell to the UE,
be unicast via dedicated signaling by the cell, or be preconfigured
to the UE (e.g., stored in a USIM and/or stored in a UICC). In some
of the present implementations, R.sub.SINR_av may be zero.
Q.sub.SINR_th_av may be cell-specific or unique for the system. If
Q.sub.SINR_th is cell-specific, it may be applied to the cell which
broadcasts the Q.sub.SINR_th value.
[0122] In some of the present implementations, the UE may derive an
SINR value for a beam. Thus, for each beam, there may be an SINR
value. There are many approaches to define the beam-specific SINR.
For example, if there are "B" beams, Q.sub.SINR_th_av may be
derived by the summation of all beam-specific SINR values divided
by "B." In another example, if there are "B" beams,
Q.sub.SINR_th_av may be derived by the summation of all received
signals of beams divided by the summation of all interference and
noise of all beams. The measurement quantity may be the SS/PBCH
block of the cell. Each SS/PBCH block of the cell may correspond to
a beam. The value of "B" may be a positive integer.
[0123] In some of the present implementations, a threshold (e.g.,
Q.sub.SINR_Beam_th) may be configured. Only the beams with an SINR
value above the threshold (e.g., Q.sub.SINR_Beam_th) may be used
for derivation of the beam-average SINR value. For example, if
there are "B1" beams with their SINR values above the threshold
(e.g., Q.sub.SINR_Beam_th), Q.sub.SINR_th_av may be derived by the
summation of the B1 beam-specific SINR values divided by "B1." In
some of the present implementations, if there are "B1" beams,
Q.sub.SINR_th_av may be derived by the summation of all received
signals of beams divided by the summation of all interference and
noise of all beams. If there are no beams with their beam-specific
SINR values above the threshold (e.g., Q.sub.SINR_Beam_th), the
highest SINR value among the beams may be used for the S criterion.
For example, the highest SINR value among the beams may be used as
Q.sub.SINR_av. In some of the present implementations, if "B1" is
higher than, or equal to, another value "B2," only the SINR values
of the B2 beams may be used to derive the beam-average SINR value.
For example, the highest "B2" SINR values among the "B1" SINR
values may be used. In another example, the lowest "B2" SINR values
among the "B1" SINR values may be used. In still another example,
the "B2" SINR values may be randomly selected from the "B 1" SINR
values. In some of the present implementations, the "B2" value may
be preconfigured or broadcast by the cell. The "B2" value may be
sent by the cell via dedicated signaling. On the other hand, the
"Q.sub.SINR_Beam_th" value may be preconfigured or broadcast by the
cell to the UE. The "Q.sub.SINR_Beam_th" value may be sent by the
cell via the dedicated signaling. The values of "B1" and "B2" may
be positive integers.
[0124] In some of the present implementations, the carrier
frequency bandwidth for the RAT on an unlicensed spectrum (e.g.,
NR-U) may be (but not limited to) 20 MHz. If wideband is
considered, the carrier frequency for the RAT on the unlicensed
spectrum may be a multiple of 20 MHz. For example, an unlicensed
carrier frequency may have a channel bandwidth of 100 MHz. For
another example, a 100 MHz bandwidth may be divided into five
different unlicensed carrier frequencies, with each having a
channel bandwidth of 20 MHz.
[0125] In some of the present implementations, the cell reselection
procedure on an unlicensed spectrum (e.g., NR-U) may consider the
(reselection) priority and ranks. In some of the present
implementations, absolute priorities of different NR frequencies,
different NR-U frequencies or inter-RAT frequencies may be provided
to the UE in the system information (e.g., SIB1, SIB2, SIB3, SIB4,
SIB5), in the dedicated signaling (e.g., RRC (Connection) Release
message, RRC (Connection) Release message with suspend
configuration, RRC (Connection) Release message without suspend
configuration), or by inheriting from another RAT during the
inter-RAT cell (re)selection. In some of the present
implementations, in the case of system information, the NR
frequency, the NR-U frequency or the inter-RAT frequency may be
listed without providing a priority (e.g., the field
cellReselectionPriority may be absent for that frequency). If the
priorities are provided in the dedicated signaling (e.g., RRC
(Connection) Release message, RRC (Connection) Release message with
suspend configuration, RRC (Connection) Release message without
suspend configuration), the UE may ignore all the priorities
provided in system information.
[0126] In some of the present implementations, if the NR and the
NR-U are considered as the same RAT, the NR frequency and the NR-U
frequency may be inter-frequencies. In some of the present
implementations, if the NR and the NR-U are considered as different
RATs, the NR frequency and the NR-U frequency may be inter-RAT
frequencies. In some of the present implementations, different
unlicensed carrier frequencies for the same RAT (e.g., NR-U) may be
considered as inter-frequencies.
[0127] In some of the present implementations, the cell may
broadcast the priority information (e.g., inter-RAT frequency
priority and/or inter-frequency priority). For example, the
priority information may be included in the SIB1 and/or other SI
(e.g., the SIB2, the SIB3, the SIB4, and the SIB5). The cell may
inform the UE of the priority information via the dedicated
signaling (e.g., an RRC Release message). In some of the present
implementations, different RATs may have different priorities
(e.g., RAT-specific priority). In some of the present
implementations, different carrier frequencies may have different
priorities, e.g., frequency-specific priority. For example, for an
E-UTRA RAT, the frequency priority information may include the
carrier frequency of E-UTRA, the cell reselection priority
corresponding to the carrier frequency, and optionally the cell
reselection sub-priority. For an NR RAT, the frequency priority
information may include the carrier frequency of NR, the cell
reselection priority corresponding to the carrier frequency, and
optionally the cell reselection sub-priority corresponding to the
carrier frequency. For an NR-U RAT, the frequency priority
information may include the carrier frequency of NR-U, the cell
reselection priority corresponding to the carrier frequency, and
optionally the cell reselection sub-priority corresponding to the
carrier frequency. In some of the present implementations, the
frequency priority information of NR RAT may include the carrier
frequency of NR-U RAT, the cell reselection priority corresponding
to the carrier frequency, and optionally the cell reselection
sub-priority corresponding to the carrier frequency.
[0128] In some of the present implementations, based on the
measurement results, the UE may rank the serving cell and the
non-serving cells (e.g., intra-frequency cells, inter-frequency
cells and inter-RAT cells). For the RAT on an unlicensed spectrum
(e.g., NR-U), the intra-frequency cells may belong to the same PLMN
as that of the serving cell, or belong to different PLMNs from that
of the serving cell. Similarly, for the RAT on the unlicensed
spectrum (e.g., NR-U), the inter-frequency cells may belong to the
same PLMN as that of the serving cell, or different PLMNs from that
of the serving cell. In some of the present implementations, the UE
may rank the serving cell and the non-serving cells (e.g.,
intra-frequency cells, inter-frequency cells and inter-RAT cells)
belonging to the same PLMN as that of the serving cell. In some of
the present implementations, the UE may rank the serving cell and
the non-serving cells (e.g., intra-frequency cells, inter-frequency
cells, inter-RAT cells), which may not exactly belong to the same
PLMN as that of the serving cell.
[0129] In some of the present implementations, the RAT on an
unlicensed spectrum may be another RAT compared to the RATs on a
licensed spectrum. For example, the NR-U having a PCell on an
unlicensed spectrum may be a RAT different from the NR (which may
be assumed to have a PCell on a licensed spectrum). For example,
the E-UTRA on a licensed spectrum may be another RAT compared to
NR-U operating on an unlicensed spectrum. In some of the present
implementations, the inter-RAT information may include the E-UTRA
specific information, the NR specific information, and NR-U
specific information.
[0130] In some of the present implementations, when evaluating
Srxlev and Squal of non-serving cells for cell reselection
purposes, the UE may use parameters provided by the serving cell.
Some rules may be used by the UE to limit required measurements. In
some of the present implementations, if the serving cell fulfills
Srxlev >S.sub.IntraSearchP and Squal >S.sub.IntrasearchQ, the
UE may choose not to perform intra-frequency measurements.
Otherwise, the UE may perform intra-frequency measurements.
S.sub.IntrasearchP may be the Srxlev threshold (in dB) for
intra-frequency measurements, for example, in terms of RSRP.
S.sub.IntrasearchQ may be the Squal threshold (in dB) for
intra-frequency measurements, for example, in terms of RSRQ. In
some of the present implementations, if the serving cell fulfils
S.sub.SINR>S.sub.IntrasearchSINR, the UE may choose not to
perform intra-frequency measurements. Otherwise, the UE may perform
intra-frequency measurements. S.sub.IntraSearchSINR may be the
threshold (in dB) for intra-frequency measurements, for example, in
terms of SINR. In some of the present implementations, if the
serving cell fulfils S.sub.SINR_av>S.sub.IntraSearchSINR_av, the
UE may choose not to perform intra-frequency measurements.
Otherwise, the UE may perform intra-frequency measurements.
S.sub.IntrasearchSINR_av may be the threshold (in dB) for
intra-frequency measurements, for example, in terms of average
SINR. If multi-beam operation on the unlicensed spectrum is used,
S.sub.IntraSearchSINR_av may be configured.
[0131] Some rules may be required for an inter-frequency cell
reselection procedure on the unlicensed spectrum(s). In some of the
present implementations, for an unlicensed inter-frequency with a
reselection priority higher than the reselection priority of the
current frequency, the UE may perform measurements on the
unlicensed inter-frequency. The current frequency may be an
unlicensed carrier frequency or a licensed carrier frequency. The
format of the cell reselection priority indicator may be N bits
corresponding to a 2.sup.N value. For example, the cell reselection
priority indicator may mean the lowest priority when its value is
0. In addition, a higher value of the cell reselection indicator
may correspond to a higher cell reselection priority. In some of
the present implementations, a cell reselection sub-priority value
may be added to the value of the cell reselection priority
indicator for the corresponding frequency or RAT. That is, the cell
reselection sub-priority value and the value of the cell
reselection priority indicator may constitute an absolute priority
value for the concerned RAT, or constitute an absolute priority
value for the concerned carrier frequency of the corresponding RAT.
In some of the present implementations, if the dedicated signaling
(e.g., the RRC (Connection) Release message, RRC Release message
with suspend configuration, RRC Release message without suspend
configuration) does not include the cell reselection priority
indicator, the UE may apply the cell reselection priority indicator
broadcast in the system information. In some of the present
implementations, if the system information does not include the
cell reselection priority indicator, the UE may apply the stored
cell reselection priority indicator. In some of the present
implementations, if the dedicated signaling and the system
information do not include the cell reselection priority indicator
for the corresponding RAT/frequency, and the UE does not store any
cell reselection priority indicator for the corresponding
RAT/frequency, the UE may apply a default value as the cell
reselection priority indicator for the corresponding RAT/frequency.
In some of the present implementations, the default value may be
zero, which means that the corresponding RAT/frequency may have the
lowest priority. In some of the present implementations, if the
dedicated signaling and the system information do not include the
cell reselection priority indicator for the corresponding
RAT/frequency and the UE does not store any cell reselection
priority indicator for the corresponding RAT/frequency, the UE may
treat the cells on the corresponding RAT/frequency as barred during
the cell reselection procedure. For inter-frequency measurements,
at least one of the SINR value, the RSSI value and the channel
occupancy ratio value may be used as the measured metrics. For
example, the UE may perform measurements on cells in different
frequencies based on the SINR values, the average SINR values, the
RSSI values or the channel occupancy ratio values. For example, the
UE may perform measurements on the frequencies based on the RSSI
values or the channel occupancy ratio values. In some of the
present implementations, the UE may deprioritize a carrier
frequency to be selected in the cell reselection procedure if the
measurement results (e.g., the RSSI values or the channel occupancy
ratio values) of such a carrier frequency is worse than the
measurement results of another frequency with a lower (reselection)
priority.
[0132] In some of the present implementations, for an unlicensed
inter-frequency with a reselection priority equal to or lower than
the reselection priority of the current frequency, if the serving
cell fulfils Srxlev >S.sub.nonIntraSearchP and Squal
>S.sub.nonIntraSearchQ, the UE may decide not to perform
measurements on the unlicensed inter-frequencies. In some of the
present implementations, if the serving cell fulfils Srxlev
>S.sub.nonIntraSearchSINR, the UE may decide not to perform
measurements on the unlicensed inter-frequencies (with a
reselection priority equal to or lower than the reselection
priority of the current frequency). S.sub.nonIntraSearchSINR may be
a threshold (in dB) for unlicensed inter-frequency measurements,
for example, in terms of SINR. In some of the present
implementations, if the serving cell fulfils Srxlev
>S.sub.nonIntraSearchSINR_av, the UE may decide not to perform
measurements on the unlicensed inter-frequencies (with a
reselection priority equal to or lower than the reselection
priority of the current frequency). S.sub.nonIntraSearchSINR_av may
be a threshold (in dB) for unlicensed inter-frequency measurements,
for example, in terms of average SINR. If the multi-beam operation
on an unlicensed spectrum is used, S.sub.nonIntraSearchSINR_av may
be configured. In some of the present implementations, if the
conditions are not fulfilled, the UE may perform measurements of
the unlicensed inter-frequencies.
[0133] In some of the present implementations, if the measured
metric value (e.g., the RSSI value or the channel occupancy ratio
value) of the current frequency is above a threshold, the UE may
not perform measurements on the unlicensed inter-frequencies,
regardless of the priority of the unlicensed inter-frequencies. The
threshold may be configured by the system information or dedicated
signaling.
[0134] In some of the present implementations, a UE (e.g., in
RRC_CONNECTED state) may report the measurement results (e.g., the
RSSI value or the channel occupancy ratio value) of different
frequencies (e.g., in the unlicensed spectrum(s) or the licensed
spectrum(s)) to the serving cell via the dedicated signaling (e.g.,
Measurement Report message). Upon receiving the measurement
results, the serving cell may adjust the (reselection) priority of
different frequencies. Thus, the cell may send the updated
(reselection) priority of different frequencies in the system
information (e.g., in the SIB1, the SIB2, the SIB3, the SIB4, or
the SIB5) or in the dedicated signaling (e.g., in an RRC
(Connection) Release message, in an RRC Release message with
suspend configuration, in an RRC Release message without suspend
configuration) to the UE. Upon acquiring the updated (reselection)
priority, the UE may replace the stored value of (reselection)
priority with the updated (reselection) priority for cell
reselection.
[0135] Some rules may be required for the inter-RAT frequency cell
reselection between the unlicensed spectrum(s) and the licensed
spectrum(s). In some of the present implementations, if the
inter-RAT frequency is unlicensed, each unlicensed carrier
frequency may correspond to a reselection priority. In some of the
present implementations, if the inter-RAT frequency is unlicensed,
all unlicensed carrier frequencies may correspond to a reselection
priority.
[0136] In some of the present implementations, if an unlicensed
inter-RAT frequency (e.g., an NR-U frequency) has a reselection
priority higher than the reselection priority of the current
licensed carrier frequency (e.g., an NR frequency or an E-UTRA
frequency), the UE may perform measurements on the unlicensed
inter-RAT frequency. In some of the present implementations, if at
least one licensed inter-RAT frequency (e.g., an NR frequency or an
E-UTRA frequency) has a reselection priority higher than the
reselection priority of the current licensed carrier frequency
(e.g., an NR frequency or an E-UTRA frequency), the UE may not
perform measurements on the unlicensed inter-RAT frequency.
[0137] In some of the present implementations, if the licensed
inter-RAT frequency (e.g., an NR frequency or an E-UTRA frequency)
has a reselection priority higher than the reselection priority of
the current unlicensed carrier frequency (e.g., an NR-U frequency),
the UE may perform measurements of the licensed inter-RAT frequency
having the higher reselection priority.
[0138] In some of the present implementations, if the measured
metric value of the current unlicensed carrier frequency (e.g., the
SINR value, the RSSI value or the channel occupancy ratio value) is
below a threshold, the UE may perform measurements on the licensed
inter-RAT frequencies (e.g., an NR frequency or an E-UTRA
frequency). In some of the present implementations, the threshold
of the corresponding measured metric value may be configured in the
system information or in the dedicated signaling, from the cell to
the UE.
[0139] In some of the present implementations, for an unlicensed
inter-RAT frequency with a reselection priority equal to or lower
than the reselection priority of the current licensed carrier
frequency, if the serving cell fulfills Srxlev
>S.sub.nonIntraSearchP and Squal >S.sub.nonIntraSearchQ, the
UE may choose not to perform measurements on the unlicensed
inter-RAT frequencies. S.sub.nonIntraSearchP may be the threshold
(in dB) for the unlicensed inter-RAT frequency measurement, for
example, in terms of RSRP. S.sub.nonIntraSearchQ may be the
threshold (in dB) for the unlicensed inter-RAT frequency
measurement, for example, in terms of RSRQ.
[0140] In some of the present implementations, for a licensed
inter-RAT frequency with a reselection priority equal to or lower
than the reselection priority of the current unlicensed carrier
frequency, if the serving cell fulfills a condition of Srxlev
>S.sub.nonIntraSearchP and Squal >S.sub.nonIntraSearchQ, the
UE may choose not to perform measurements on the licensed inter-RAT
frequency. In some of the present implementations, for a licensed
inter-RAT frequency with a reselection priority equal to or lower
than the reselection priority of the current unlicensed carrier
frequency, if the serving cell fulfills a condition of Srxlev
>S.sub.nonIntraSearchSINR, the UE may choose not to perform
measurements on the licensed inter-RAT frequency.
S.sub.nonIntraSearchSINR may be the threshold (in dB) for the
licensed inter-RAT frequency measurement, for example, in terms of
SINR. In some of the present implementations, for a licensed
inter-RAT frequency with a reselection priority equal to or lower
than the reselection priority of the current unlicensed carrier
frequency, if the serving cell fulfills a condition of Srxlev
>S.sub.nonIntraSearchSINR_av, the UE may choose not to perform
measurements on the licensed inter-RAT frequency.
S.sub.nonIntraSearchSINR_av may be the threshold (in dB) for the
licensed inter-RAT frequency measurement, for example, in terms of
average SINR. If the multi-beam operation on the unlicensed
spectrum(s) is used, S.sub.nonIntraSearchSINR_av may be configured.
In some of the present implementations, if the conditions mentioned
above are not fulfilled, the UE may perform measurements of the
licensed inter-RAT frequencies.
[0141] In some of the present implementations, if the
highest-ranked cell (or the best cell or the strongest cell) on an
unlicensed carrier frequency (e.g., the highest-ranked cell is an
unlicensed intra-frequency cell or an unlicensed inter-frequency
cell) is not suitable to camp on because the highest-ranked cell is
a part of the "list of 5G System (5GS) forbidden Tracking Areas
(TAs) for roaming", or belongs to a PLMN which is not indicated as
being equivalent to the registered PLMN, the highest-ranked cell is
barred, the UE may consider the highest-ranked cell as a
non-suitable cell to camp on for a maximum time period of T (e.g.,
300) seconds. In this case, the UE may consider other cells as
candidate cells on the same unlicensed carrier frequency for the
cell reselection procedure.
[0142] Cells on the unlicensed carrier frequency may be ranked
based on their corresponding measured metric values or other
absolute priority reselection rules. For example, the
highest-ranked cell may be the cell having the best received radio
signal quality among cells on the same carrier frequency. It should
be noted that the "highest-ranked cell," the "best cell," and the
"strongest cell," may be interchangeable terms in some of the
present implementations.
[0143] In some of the present implementations, the T value for the
licensed intra-frequency cell case or for the licensed
inter-frequency cell case may be independent of the T value for the
unlicensed intra-frequency cell case or for the unlicensed
inter-frequency cell case. The T values may be independently
configured or predefined for different cases, and the T values may
be different. In some of the present implementations, the T value
for the licensed intra-frequency cell case or for the licensed
inter-frequency cell case may be the same as the T value for the
unlicensed intra-frequency cell case or for the unlicensed
inter-frequency cell case. In some of such implementations, the T
values for different cases may be configured or predefined
together.
[0144] In some of the present implementations, if the
highest-ranked cell on an unlicensed carrier frequency is a
non-suitable cell to camp on (e.g., the UE determines that the
highest-ranked cell is not suitable for camping on), the UE may not
consider cells on the same unlicensed carrier frequency as
candidate suitable cells for reselection for a maximum time period
of T (e.g., 300) seconds, if at least one cell on other frequencies
is ranked by the UE and has a rank value higher than a rank
threshold. The rank threshold may be preconfigured, broadcast by
the serving cell (e.g., in the SIB2, the SIB3, the SIB4 or the
SIB5), or sent via the RRC dedicated signaling (e.g., in an RRC
(Connection) Release message, in an RRC Release message with
suspend configuration, in an RRC Release message without suspend
configuration).
[0145] In some of the present implementations, if the
highest-ranked cell on an unlicensed carrier frequency is not
suitable for camping on, the UE may consider cells on the same
unlicensed carrier frequency as non-suitable cells for a maximum
time period of T seconds if at least one cell on other frequencies
fulfills the cell selection criterion S.
[0146] In some of the present implementations, if the
highest-ranked cell on an unlicensed carrier frequency is
determined as a non-suitable cell, the UE may further consider
cells on the same unlicensed carrier frequency as non-suitable
cells for a maximum time period of T (e.g., 300) seconds if the
measured metric value (e.g., the RSRP value, the RSRQ value or the
SINR value) of at least one cell on other frequencies is above a
threshold. The threshold may be preconfigured, broadcast by the
serving cell (e.g., in the SIB2, the SIB3, the SIB4, the SIB5), or
sent via the RRC dedicated signaling (e.g., in an RRC (Connection)
Release message, in an RRC Release message with suspend
configuration, in an RRC Release message without suspend
configuration).
[0147] In some of the present implementations, the UE may be
redirected, under the licensed RAT (e.g., NR)'s control, to an
unlicensed carrier frequency (e.g., to utilize the unlicensed RAT
such as the NR-U). If the UE is redirected, under the licensed
RAT's control, to the unlicensed carrier frequency for which a
timer T is running, any limitation on that unlicensed carrier
frequency may be removed. The limitation may include any
restriction from allowing the UE to perform cell (re)selection
procedures on that unlicensed carrier frequency. For example, the
UE may remove the limitation on that unlicensed carrier frequency
by stopping the timer T. Thus, the UE may perform measurements on
that unlicensed carrier frequency.
[0148] In some of the present implementations, the UE may be
redirected, under the unlicensed RAT (e.g., NR-U)'s control, to a
licensed carrier frequency (e.g., NR). If the UE is redirected
under unlicensed RAT (e.g., NR-U) control to a licensed carrier
frequency for which the timer T is running, any limitation on that
licensed carrier frequency may be removed. The limitation may
include any restriction from allowing the UE to perform cell
(re)selection procedures on that licensed carrier frequency. For
example, the UE may remove the limitation on that licensed carrier
frequency by stopping the timer T. Thus, the UE may perform
measurements on that licensed carrier frequency.
[0149] In some of the present implementations, if an indication
(e.g., thresServingLowSINR) is broadcast in the system information
and more than Tr (e.g., 1) second has elapsed since the UE began
camping on the current serving cell, the UE may perform a cell
reselection procedure to select a cell (e.g., a new suitable cell
to camp on) on a higher priority frequency than the serving
frequency. The cell of a higher priority RAT, a licensed carrier
frequency or an unlicensed carrier frequency may fulfill that the
SINR value of the cell is above a threshold (e.g., Thresh.sub.X,
HighSINR) during a time interval (e.g., Treselection.sub.RAT).
Otherwise, the cell reselection to the cell on the higher priority
frequency (e.g., an intra-frequency or an inter-frequency) than the
serving frequency may be performed if the cell fulfills
Srxlev>Thresh.sub.X, HighP during a time interval (e.g.,
Treselection.sub.RAT) and more than 1 second has elapsed since the
UE began camping on the current serving cell.
[0150] In some of the present implementations, the frequency
channel of the selected cell (e.g., the new suitable cell during
the cell reselection procedure), which may correspond to a higher
priority RAT, licensed carrier frequency or unlicensed carrier
frequency, may fulfill that the RSSI value of the frequency is
above a threshold (e.g., Thresh.sub.X, HighRSSI) during a time
interval (e.g., Treselection.sub.RAT). Otherwise, the cell
reselection to the cell on a higher priority frequency (e.g., an
intra-frequency or an inter-frequency) than the serving frequency
may be performed, if the cell fulfills Srxlev>Thresh.sub.X,
HighP during a time interval (e.g., Treselection.sub.RAT) and more
than 1 second has elapsed since the UE began camping on the current
serving cell.
[0151] In some of the present implementations, if an indication
(e.g., thresServingLowCO) is broadcast in the system information
and more than Tr (e.g., 1) second has elapsed since the UE camped
on the current serving cell, the UE may perform a cell reselection
to a cell on a higher priority frequency than the serving
frequency. The frequency channel of a cell, of a higher priority
RAT, licensed carrier frequency or unlicensed carrier frequency,
may fulfill that the channel occupancy ratio value of the frequency
is above a threshold (e.g., Thresh.sub.X, HighCO) during a time
interval (e.g., Treselection.sub.RAT). Otherwise, the cell
reselection to the cell on the higher priority frequency (e.g., an
intra-frequency or an inter-frequency) than the serving frequency
may be performed if the cell fulfills Srxlev>Thresh.sub.X, HighP
during a time interval (e.g., Treselection.sub.RAT) and more than 1
second has elapsed since the UE began camping on the current
serving cell.
[0152] In some of the present implementations, if there is no
special indicator (e.g., thresServingLowSINR, thresServingLowRSSI,
thresServingLowCO) broadcast in the system information and more
than Tr (e.g., 1) second has elapsed since the UE began camping on
the current serving cell, the UE may perform a cell reselection to
a cell on a higher priority frequency than the serving frequency.
The selected cell (e.g., a new suitable cell to camp on) may
fulfill that a cell selection RX level value based on RSRP (e.g.,
Srxlev) is above a threshold (e.g., Thresh.sub.X, HighP) during a
timer interval (e.g., Treselection.sub.RAT).
[0153] In some of the present implementations, the mechanisms
mentioned above may be applied to a cell reselection procedure to
change the original suitable cell of the UE from a cell in the
licensed carrier frequency to a cell in the unlicensed carrier
frequency, or from a cell in the unlicensed carrier frequency to a
cell in the licensed carrier frequency, or from a cell in the
unlicensed carrier frequency to a cell in the unlicensed carrier
frequency, or from a cell in the licensed carrier frequency to a
cell in the licensed carrier frequency.
[0154] In some of the present implementations, if a UE camping on a
cell in a source frequency reselects to a cell in a target
frequency, the UE may start a timer based on a timer value. Before
the timer expires, the UE may not measure and/or reselect a cell in
the source frequency. The UE may be configured with the timer value
via the system information (e.g., the SIB1, other SI (e.g., the
SIB2 or the SIB3)) or the dedicated signaling (e.g., the RRC
(Connection) Release message, the suspend configuration in the RRC
Release message, the RRC Release message with suspend
configuration, the RRC Release message without suspend
configuration) by the cell on the source frequency. In some of the
present implementations, the timer value may be preconfigured or
predefined. In some of the present implementations, the UE may stop
the timer if the UE cannot reselect any cell in another frequency.
In other words, the UE may deprioritize the source frequency to the
lowest priority among all available frequencies (e.g., when the
timer is running). In some of the present implementations, if the
UE camping on a target cell reselects to another target cell in the
third frequency, the UE may stop the timer for the source
frequency. Moreover, the UE may start the timer for the target
frequency.
[0155] In some of the present implementations, the UE may rank all
cells on the unlicensed intra-frequency or unlicensed
inter-frequency that fulfill the cell selection criterion S. The UE
may rank cells based on the cell-ranking criterion R.sub.s for the
serving cell and R.sub.n for neighboring cells. In some of the
present implementations, the cell-ranking criterion R.sub.s for the
unlicensed serving cell and the cell-ranking criterion R.sub.n for
the unlicensed neighboring cells (e.g., in the unlicensed
intra-frequency or in the equal priority unlicensed
inter-frequency) may be defined by R.sub.s=Q.sub.meas, s+Q.sub.rmd,
s and R.sub.n=Q.sub.meas, n+Q.sub.rmd, n, where Q.sub.meas, s may
be the measured metric value (e.g., the RSRP value, the RSRQ value,
or the SINR value) used in the cell reselection procedure,
Q.sub.rmd, s may be the adjusted item (e.g., a hysteresis value),
Q.sub.meas, n may be the measured metric value used in the cell
reselection procedure, and Q.sub.rmd, n may be the adjusted item
(e.g., offset values depending on the unlicensed intra-frequency or
inter-frequency). The comparison between R.sub.s and R.sub.n may be
based on the same measured metric. In some of the present
implementations, the UE may receive the values of Q.sub.rmd, s and
Q.sub.rmd, n via the system information (e.g., the SIB2, the SIB3,
the SIB4, the SIB5 or others) or via the dedicated signaling (e.g.,
an RRC (Connection) Release message, RRC
[0156] Release message with suspend configuration, RRC Release
message without suspend configuration) from the serving cell.
[0157] In some of the present implementations, the UE may rank the
(unlicensed) cells according to the R criteria and calculate the R
values (e.g., R.sub.s and R.sub.n) using the averaged measured
metric results (e.g., the averaged RSRP/RSRQ/SINR values) of the
corresponding cells.
[0158] In some of the present implementations, the UE may re-rank
the cells based on the UE's registered PLMN or equivalent PLMN. The
re-ranked cell ranking list may include all cells belonging to the
same PLMN. For example, the UE may re-rank the cells by removing
the cells not belonging to the registered PLMN or equivalent PLMN
from the original cell ranking list. In this case, the original
cell ranking list may include cells belonging to different
PLMNs.
[0159] In some of the present implementations, the UE may base on
the signal-strength-related measurement quantity (e.g., RSRP, RSRQ,
SINR) to rank the cells. The cells belonging to different PLMNs on
the same carrier frequency may be ranked together, which we may
refer to "original cell ranking list". If the re-rank rule is
applied, the re-ranked cell ranking list may include all cells
belonging to the UE's registered PLMN or equivalent PLMN. In some
of the present implementations, the UE may perform the cell
reselection procedure based on the original cell ranking list. In
some of the present implementations, the UE may perform the cell
reselection procedure based on the re-ranked cell ranking list. In
some of the present implementations, the UE may use the re-ranked
cell ranking list to perform an intra-frequency cell reselection
procedure and/or an inter-frequency cell reselection procedure. For
example, the UE may (re)select the highest-ranked cell among cells
listed in the re-ranked cell ranking list on the licensed
spectrum(s). For another example, the UE may reselect the
highest-ranked cell among cells listed in the re-ranked cell
ranking lists on the unlicensed spectrum(s). For example, the UE
may (re)select the highest-ranked cell among cells listed in the
re-ranked cell ranking list including cells on the licensed
spectrum(s) and unlicensed spectrum(s) and belonging to the same
PLMN. In some of the present implementations, the cell ranking list
on the licensed spectrum(s) may be regarded as a re-rank cell
ranking list if the cell ranking list on the licensed spectrum(s)
includes cells belonging to the same PLMN.
[0160] In some of the present implementations, if the UE has at
least two original cell ranking lists wherein each list is
corresponding to one unlicensed carrier frequency, the UE may
select a cell that satisfies the following two conditions as a
suitable cell: (1) the cell belongs to the
selected/registered/equivalent PLMN, and (2) the cell is the
highest-ranked cell among cells listed in the at least two original
cell ranking lists. Furthermore, the selected cell may not be
barred.
[0161] In some of the present implementations, if the indication
(e.g., rangeToBestCell) is not configured, the UE may perform the
cell reselection procedure to select a new suitable cell ranked as
the best cell. The best cell may be listed in the original cell
ranking list or the re-ranked cell ranking list. In some of the
present implementations, if the best cell (or the highest-ranked
cell) is found to be non-suitable (e.g., not belonging to the UE's
registered PLMN or equivalent PLMN, not fulfilling cell selection
criterion S), the UE may select the next best cell (or the next
highest-ranked cell) as the new suitable cell. The ranking of the
next best cell (or the next highest-ranked cell) is lower than that
of the best cell (or the highest-ranked cell).
[0162] In some of the present implementations, if the UE finds a
selected cell to be non-suitable (e.g., not belonging to the UE's
registered PLMN or equivalent PLMN), the UE may select the next
cell whose ranking is the next lower to the previously selected
non-suitable cell. In some of the present implementations, if the
best cell is found to be non-suitable (e.g., not belonging to the
UE's registered PLMN or equivalent PLMN, not fulfilling cell
selection criterion S), the UE may remove the cells belonging to
the same PLMN as the best cell in the original cell ranking
list.
[0163] In some of the present implementations, if the indication
(e.g., rangeToBestCell) is configured, the UE may perform a cell
reselection procedure to select a new suitable cell. The new
suitable cell may have the highest number of beams above a
threshold (e.g., an SINR-valued threshold, an RSRP-valued
threshold, or an RSRQ-valued threshold) among the cells whose R
value is within the indication (e.g., rangeToBestCell) of the R
value of the cell ranked as the best cell. For example, if the UE
calculates the R value of a cell based on an (averaged) SINR value,
the UE may count the number of beams above an SINR-valued threshold
of the cell. In some of the present implementations, if there are
multiple such cells, the UE may perform the cell reselection
procedure to select the highest-ranked cell among them.
[0164] In some of the present implementations, if the indication
(e.g., rangeToBestCell) is configured, the UE may perform a cell
reselection procedure to select a new suitable cell belonging to
the UE's registered PLMN (or equivalent PLMN) and having the
highest number of beams above a threshold (e.g., an SINR-valued
threshold, an RSRP-valued threshold, or an RSRQ-valued threshold)
among the cells whose R value is within the indication (e.g.,
rangeToBestCell) of the R value of the cell ranked as the best
cell. In some of the present implementations, the best cell may be
listed in a re-ranked cell list. In some of the present
implementations, the best cell may or may not belong to the UE's
registered PLMN (or equivalent PLMN). For example, if the UE
calculates the R value of a cell based on an (averaged) SINR value,
the UE may count the number of beams above an SINR-valued threshold
of the cell. In some of the present implementations, if there are
multiple such cells, the UE may perform the cell reselection
procedure to select the highest-ranked cell among them.
[0165] In some of the present implementations, the cell may
broadcast a channel occupancy ratio value or an RSSI value based on
the cell's measurement on the unlicensed carrier frequency. If the
cell's broadcast channel occupancy ratio value is above a
threshold, the UE may not (re)select such a cell as a suitable cell
to camp on. Similarly, if the cell's broadcast RSSI value is below
a threshold, the UE may not (re)select such a cell as a suitable
cell. In some of the present implementations, if the cell's
broadcast channel occupancy ratio value is above a threshold, the
UE may perform an inter-frequency cell reselection procedure or an
inter-RAT cell reselection procedure to search for a new suitable
cell in other frequencies.
[0166] In some of the present implementations, if the cell's
broadcast RSSI value is below a threshold, the UE may perform an
inter-frequency cell reselection procedure or an inter-RAT cell
reselection procedure to search for a new suitable cell in other
frequencies. If the UE receives the multiple RSSI values from the
cell, the UE may compare the average value of the RSSI values with
the threshold. In some of the present implementations, the
threshold may be broadcast to the UE or sent to the UE via the
dedicated signaling. In some of the present implementations, the
threshold may be a pre-defined value (e.g., determined based on UE
categories, UE target service types, or other UE characteristics).
In some of the present implementations, the UE may adjust the
cell's rank based on the cell's broadcast channel occupancy ratio
value or RSSI value.
[0167] In some of the present implementations, the mentioned
dedicated signaling may refer to (but not limited to) RRC
message(s). The cell may transmit the dedicated signaling to the
UE, wherein the dedicated signaling may be RRC (Connection) Setup
message, RRC (Connection) Reconfiguration message, RRC Connection
Reconfiguration message including the mobility control information,
RRC Connection Reconfiguration message without the mobility control
information inside, RRC Reconfiguration message including the
configuration with sync, RRC Reconfiguration message without the
configuration with sync inside, RRC (Connection) Resume message,
RRC (Connection) Reestablishment message, RRC (Connection) Reject
message, RRC
[0168] (Connection) Release message, RRC Release message including
suspend configuration, RRC Release message without suspend
configuration inside and UE Capability Enquiry message, etc. The UE
may transmit the dedicated signaling to the cell, wherein the
dedicated signaling may be RRC (Connection) Setup Request message,
RRC (Connection) Setup Complete message, RRC (Connection)
Reconfiguration Complete message, RRC (Connection) Resume Request
message, RRC (Connection) Resume Complete message, RRC (Connection)
Reestablishment Request message, RRC (Connection) Reestablishment
Complete message, RRC System Information Request message, UE
Assistance Information message, and UE Capability Information
message, etc.
[0169] The RRC_IDLE/RRC_INACTIVE UE may camp on a cell, which may
refer to a "camped cell". The RRC_CONNECTED UE may be served by a
serving cell. The serving cell may be a camped cell to the UE when
the UE enters in RRC_IDLE/RRC_INACTIVE. The camped cell may be a
serving cell to the UE when the UE enters in RRC_CONNECTED. If the
UE can measure the radio signal strength from a cell, such cell may
be a detected cell to the UE.
[0170] FIG. 8 is a block diagram illustrating a node for wireless
communication, in accordance with various aspects of the present
disclosure. As shown in FIG. 8, a node 800 may include a
transceiver 820, a processor 828, a memory 834, one or more
presentation components 838, and at least one antenna 836. The node
800 may also include an RF spectrum band module, a BS
communications module, a network communications module, and a
system communications management module, Input/Output (I/O) ports,
I/O components, and power supply (not explicitly shown in FIG. 8).
Each of these components may be in communication with each other,
directly or indirectly, over one or more buses 840. In one
implementation, the node 800 may be a UE, a BS, or any other
apparatus of wireless communications that performs various
functions described herein, for example, with reference to FIGS. 1
through 7.
[0171] The transceiver 820 having a transmitter 822 (e.g.,
transmitting/transmission circuitry) and a receiver 824 (e.g.,
receiving/reception circuitry) may be configured to transmit and/or
receive time and/or frequency resource partitioning information. In
some of the present implementations, the transceiver 820 may be
configured to transmit in different types of subframes and slots
including, but not limited to, usable, non-usable and flexibly
usable subframes and slot formats. The transceiver 820 may be
configured to receive data and control channels.
[0172] The node 800 may include a variety of computer-readable
media. Computer-readable media may be any available media that may
be accessed by the node 800 and include both volatile (and
non-volatile) media, and removable (and non-removable) media. By
way of example, and not limitation, computer-readable media may
comprise computer storage media and communication media. Computer
storage media may include both volatile (and/or non-volatile), as
well as removable (and/or non-removable) media implemented in any
method or technology for storage of information such as
computer-readable instructions, data structures, program modules or
data.
[0173] Computer storage media may include RAM, ROM, EEPROM, flash
memory or other memory technology, CD-ROM, Digital Versatile Disks
(DVD) or other optical disk storage, magnetic cassettes, magnetic
tape, magnetic disk storage or other magnetic storage devices.
Computer storage media do not comprise a propagated data signal.
Communication media may typically embody computer-readable
instructions, data structures, program modules or other data in a
modulated data signal such as a carrier wave or other transport
mechanism and includes any information delivery media. The term
"modulated data signal" may mean a signal that has one or more of
its characteristics set or changed in such a manner as to encode
information in the signal. By way of example, and not limitation,
communication media may include wired media such as a wired network
or direct-wired connection, and wireless media such as acoustic,
RF, infrared and other wireless media. Combinations of any of the
above should also be included within the scope of computer-readable
media.
[0174] The memory 834 may include computer-storage media in the
form of volatile and/or non-volatile memory. The memory 834 may be
removable, non-removable, or a combination thereof. Example memory
includes solid-state memory, hard drives, optical-disc drives, etc.
As illustrated in FIG. 8, the memory 834 may store
computer-readable and computer-executable instructions 832 (e.g.,
software codes) that are configured to, when executed, cause the
processor 828 to perform various functions described herein, for
example, with reference to FIGS. 1 through 7. Alternatively, the
instructions 832 may not be directly executable by the processor
828 but be configured to cause the node 800 (e.g., when compiled
and executed) to perform various functions described herein.
[0175] The processor 828 (e.g., having processing circuitry) may
include an intelligent hardware device, e.g., a Central Processing
Unit (CPU), a microcontroller, an ASIC, etc. The processor 828 may
include memory. The processor 828 may process the data 830 and the
instructions 832 received from the memory 834, and information
through the transceiver 820, the baseband communications module,
and/or the network communications module. The processor 828 may
also process information to be sent to the transceiver 820 for
transmission through the antenna 836, to the network communications
module for transmission to a core network.
[0176] One or more presentation components 838 may present data
indications to a person or other device. Examples of presentation
components 838 may include a display device, speaker, printing
component, vibrating component, etc.
[0177] From the above description, it is manifested that various
techniques may be used for implementing the concepts described in
the present application without departing from the scope of those
concepts. Moreover, while the concepts have been described with
specific reference to certain implementations, a person of ordinary
skill in the art may recognize that changes may be made in form and
detail without departing from the scope of those concepts. As such,
the described implementations are to be considered in all respects
as illustrative and not restrictive. It should also be understood
that the present application is not limited to the particular
implementations described above, but many rearrangements,
modifications, and substitutions are possible without departing
from the scope of the present disclosure.
* * * * *